diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/pull_request_template.md
similarity index 100%
rename from .github/PULL_REQUEST_TEMPLATE.md
rename to .github/pull_request_template.md
diff --git a/Gemfile.lock b/Gemfile.lock
index 4614245..39196f2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    zai_payment (1.3.2)
+    zai_payment (2.0.0)
       base64 (~> 0.3.0)
       faraday (~> 2.0)
       openssl (~> 3.3)
diff --git a/CHANGELOG.md b/changelog.md
similarity index 72%
rename from CHANGELOG.md
rename to changelog.md
index 97cc593..b09a453 100644
--- a/CHANGELOG.md
+++ b/changelog.md
@@ -1,5 +1,32 @@
 ## [Released]
 
+## [2.0.0] - 2025-10-24
+### Added
+- **Items Management API**: Full CRUD operations for managing Zai items (transactions/payments) 🛒
+  - `ZaiPayment.items.list(limit:, offset:)` - List all items with pagination
+  - `ZaiPayment.items.show(item_id)` - Get item details by ID
+  - `ZaiPayment.items.create(**attributes)` - Create new item/transaction
+  - `ZaiPayment.items.update(item_id, **attributes)` - Update item information
+  - `ZaiPayment.items.delete(item_id)` - Delete an item
+  - `ZaiPayment.items.show_seller(item_id)` - Get seller details for an item
+  - `ZaiPayment.items.show_buyer(item_id)` - Get buyer details for an item
+  - `ZaiPayment.items.show_fees(item_id)` - Get fees associated with an item
+  - `ZaiPayment.items.show_wire_details(item_id)` - Get wire transfer details for an item
+  - `ZaiPayment.items.list_transactions(item_id, limit:, offset:)` - List transactions for an item
+  - `ZaiPayment.items.list_batch_transactions(item_id, limit:, offset:)` - List batch transactions for an item
+  - `ZaiPayment.items.show_status(item_id)` - Get current status of an item
+- Comprehensive validation for item attributes (name, amount, payment_type, buyer_id, seller_id)
+- Support for optional item fields (description, currency, fee_ids, custom_descriptor, deposit_reference, etc.)
+- Full RSpec test suite for Items resource with 100% coverage
+- Comprehensive examples documentation in `examples/items.md`
+
+### Documentation
+- Added detailed Items API examples with complete workflow demonstrations
+- Payment types documentation (1-7: Direct Debit, Credit Card, Bank Transfer, Wallet, BPay, PayPal, Other)
+- Error handling examples for Items operations
+
+**Full Changelog**: https://github.com/Sentia/zai-payment/compare/v1.3.2...v2.0.0
+
 ## [1.3.2] - 2025-10-23
 ### Added
 - YARD documentation generation support with `.yardopts` configuration
@@ -32,7 +59,7 @@
   - Comprehensive validation for all user types
   - Email format validation
   - Country code validation (ISO 3166-1 alpha-3)
-  - Date of birth format validation (YYYYMMDD)
+  - Date of birth format validation (DD/MM/YYYY)
   - User type validation (payin/payout)
   - Progressive profile building support
 
@@ -44,7 +71,7 @@
 - **Main Module**: Added `users` accessor for convenient access to User resource
 
 ### Documentation
-- **NEW**: [User Management Guide](docs/USERS.md) - Comprehensive guide covering:
+- **NEW**: [User Management Guide](docs/users.md) - Comprehensive guide covering:
   - Overview of payin vs payout users
   - Required fields for each user type
   - Complete API reference with examples
@@ -64,10 +91,10 @@
   - User profile validation helper
   - RSpec integration tests
   - Common patterns with retry logic
-- **NEW**: [User Quick Reference](docs/USER_QUICK_REFERENCE.md) - Quick lookup for common operations
+- **NEW**: [User Quick Reference](docs/user_quick_reference.md) - Quick lookup for common operations
 - **NEW**: [User Demo Script](examples/user_demo.rb) - Interactive demo of all user operations
-- **NEW**: [Implementation Summary](IMPLEMENTATION.md) - Detailed summary of the implementation
-- **Updated**: README.md - Added Users section with quick examples and updated roadmap
+- **NEW**: [Implementation Summary](implementation.md) - Detailed summary of the implementation
+- **Updated**: readme.md - Added Users section with quick examples and updated roadmap
 
 ### Testing
 - 40+ new test cases for User resource
@@ -97,24 +124,24 @@
   - Support for multiple signatures (key rotation scenarios)
 
 ### Documentation
-- **NEW**: [Authentication Guide](docs/AUTHENTICATION.md) - Comprehensive guide covering:
+- **NEW**: [Authentication Guide](docs/authentication.md) - Comprehensive guide covering:
   - Short way: `ZaiPayment.token` (one-liner approach)
   - Long way: `TokenProvider.new(config:).bearer_token` (advanced control)
   - Token lifecycle and automatic management
   - Multiple configurations, testing, error handling
   - Best practices and troubleshooting
-- **NEW**: [Webhook Security Quick Start](docs/WEBHOOK_SECURITY_QUICKSTART.md) - 5-minute setup guide
-- **NEW**: [Webhook Signature Implementation](docs/WEBHOOK_SIGNATURE.md) - Technical details
-- **NEW**: [Documentation Index](docs/README.md) - Central navigation for all docs
+- **NEW**: [Webhook Security Quick Start](docs/webhook_security_quickstart.md) - 5-minute setup guide
+- **NEW**: [Webhook Signature Implementation](docs/webhook_signature.md) - Technical details
+- **NEW**: [Documentation Index](docs/readme.md) - Central navigation for all docs
 - **Enhanced**: [Webhook Examples](examples/webhooks.md) - Added 400+ lines of examples:
   - Complete Rails controller implementation
   - Sinatra example
   - Rack middleware example
   - Background job processing pattern
   - Idempotency pattern
-- **Enhanced**: [Webhook Technical Guide](docs/WEBHOOKS.md) - Added 170+ lines on security
+- **Enhanced**: [Webhook Technical Guide](docs/webhooks.md) - Added 170+ lines on security
 - **Reorganized**: All documentation moved to `docs/` folder for better organization
-- **Updated**: README.md - Now concise with clear links to detailed documentation
+- **Updated**: readme.md - Now concise with clear links to detailed documentation
 
 ### Testing
 - 56 new test cases for webhook signature verification
diff --git a/CODE_OF_CONDUCT.md b/code_of_conduct.md
similarity index 100%
rename from CODE_OF_CONDUCT.md
rename to code_of_conduct.md
diff --git a/CONTRIBUTING.md b/contributing.md
similarity index 98%
rename from CONTRIBUTING.md
rename to contributing.md
index 5eeb47c..7f20c79 100644
--- a/CONTRIBUTING.md
+++ b/contributing.md
@@ -23,7 +23,7 @@ First off, thank you for considering contributing to Zai Payment! 🎉 It's peop
 
 ## Code of Conduct
 
-This project and everyone participating in it is governed by our [Code of Conduct](CODE_OF_CONDUCT.md). By participating, you are expected to uphold this code. Please report unacceptable behavior to [contact@sentia.com.au](mailto:contact@sentia.com.au).
+This project and everyone participating in it is governed by our [Code of Conduct](code_of_conduct.md). By participating, you are expected to uphold this code. Please report unacceptable behavior to [contact@sentia.com.au](mailto:contact@sentia.com.au).
 
 ---
 
@@ -86,7 +86,7 @@ Please follow these steps to have your contribution considered by the maintainer
 **Pull Request Guidelines:**
 - Keep changes focused - one feature/fix per PR
 - Link any relevant issues in the PR description
-- Update CHANGELOG.md if appropriate
+- Update changelog.md if appropriate
 - Maintain backward compatibility when possible
 - Include tests for new functionality
 - Follow the existing code style
@@ -268,9 +268,9 @@ bundle exec rubocop -a
 
 - **Public APIs must be documented** using YARD syntax
 - **Include examples** in documentation when helpful
-- **Update README.md** when adding new features
+- **Update readme.md** when adding new features
 - **Update relevant docs/** files for architectural changes
-- **Keep CHANGELOG.md** updated with notable changes
+- **Keep changelog.md** updated with notable changes
 
 **YARD Documentation Example:**
 ```ruby
diff --git a/docs/ARCHITECTURE.md b/docs/architecture.md
similarity index 100%
rename from docs/ARCHITECTURE.md
rename to docs/architecture.md
diff --git a/docs/AUTHENTICATION.md b/docs/authentication.md
similarity index 99%
rename from docs/AUTHENTICATION.md
rename to docs/authentication.md
index 94fc433..608c4a1 100644
--- a/docs/AUTHENTICATION.md
+++ b/docs/authentication.md
@@ -641,7 +641,7 @@ Gets or refreshes the bearer token.
 ## Next Steps
 
 - ✅ Authentication configured and working
-- 📖 Read [Webhook Guide](WEBHOOKS.md) to start using webhooks
+- 📖 Read [Webhook Guide](webhooks.md) to start using webhooks
 - 💡 Check [Examples](../examples/webhooks.md) for complete code samples
-- 🔒 Set up [Webhook Security](WEBHOOK_SECURITY_QUICKSTART.md)
+- 🔒 Set up [Webhook Security](webhook_security_quickstart.md)
 
diff --git a/docs/items.md b/docs/items.md
new file mode 100644
index 0000000..c838b4f
--- /dev/null
+++ b/docs/items.md
@@ -0,0 +1,666 @@
+# Item Management
+
+The Item resource provides methods for managing Zai items, which represent transactions or payments between buyers and sellers on your platform.
+
+## Overview
+
+Items are the core transactional objects in Zai that represent a payment agreement between a buyer (payin user) and a seller (payout user). Each item tracks:
+- Transaction amount
+- Payment type
+- Buyer and seller information
+- Fees and charges
+- Transaction state and history
+- Wire transfer details (if applicable)
+
+## References
+
+- [Zai Items API](https://developer.hellozai.com/reference/listitems)
+- [Create Item](https://developer.hellozai.com/reference/createitem)
+- [Update Item](https://developer.hellozai.com/reference/updateitem)
+
+## Usage
+
+### Initialize the Item Resource
+
+```ruby
+# Using the singleton instance (recommended)
+items = ZaiPayment.items
+
+# Or create a new instance
+items = ZaiPayment::Resources::Item.new
+```
+
+## Methods
+
+### Create Item
+
+Create a new item (transaction/payment) between a buyer and a seller.
+
+#### Required Fields
+
+- `name` - Name/description of the item
+- `amount` - Amount in cents (e.g., 10000 = $100.00)
+- `payment_type` - Payment type (1-7, default: 2 for credit card)
+- `buyer_id` - Buyer user ID
+- `seller_id` - Seller user ID
+
+#### Optional Fields
+
+- `id` - Custom unique ID for the item
+- `fee_ids` - Array of fee IDs to apply
+- `description` - Detailed description
+- `currency` - Currency code (e.g., 'AUD', 'USD')
+- `custom_descriptor` - Custom text for bank statements
+- `buyer_url` - URL for buyer to access transaction
+- `seller_url` - URL for seller to access transaction
+- `tax_invoice` - Whether to generate a tax invoice (boolean)
+
+#### Example
+
+```ruby
+response = ZaiPayment.items.create(
+  name: "Product Purchase",
+  amount: 10000, # $100.00 in cents
+  payment_type: 2, # Credit card
+  buyer_id: "buyer-123",
+  seller_id: "seller-456",
+  description: "Purchase of premium product XYZ",
+  currency: "AUD",
+  buyer_url: "https://buyer.example.com",
+  seller_url: "https://seller.example.com",
+  tax_invoice: true
+)
+
+if response.success?
+  item = response.data
+  puts "Item created: #{item['id']}"
+  puts "Amount: #{item['amount']}"
+  puts "State: #{item['state']}"
+end
+```
+
+#### Create Item with Custom ID
+
+```ruby
+response = ZaiPayment.items.create(
+  id: "my-custom-item-#{Time.now.to_i}",
+  name: "Custom ID Product",
+  amount: 15000,
+  payment_type: 2,
+  buyer_id: "buyer-123",
+  seller_id: "seller-456"
+)
+```
+
+### List Items
+
+Retrieve a list of all items with pagination and optional filtering.
+
+```ruby
+# List items with default pagination (10 items)
+response = ZaiPayment.items.list
+
+if response.success?
+  items_list = response.data
+  items_list.each do |item|
+    puts "Item: #{item['name']} - $#{item['amount'] / 100.0}"
+  end
+  
+  # Access pagination metadata
+  meta = response.meta
+  puts "Total items: #{meta['total']}"
+end
+```
+
+#### List with Pagination
+
+```ruby
+# Get 20 items starting from offset 40
+response = ZaiPayment.items.list(limit: 20, offset: 40)
+```
+
+#### Search Items
+
+```ruby
+# Search items by description
+response = ZaiPayment.items.list(search: "product")
+
+# Filter by creation date
+response = ZaiPayment.items.list(
+  created_after: "2024-01-01T00:00:00Z",
+  created_before: "2024-12-31T23:59:59Z"
+)
+
+# Combine filters
+response = ZaiPayment.items.list(
+  limit: 50,
+  search: "premium",
+  created_after: "2024-01-01T00:00:00Z"
+)
+```
+
+### Show Item
+
+Get details of a specific item by ID.
+
+```ruby
+response = ZaiPayment.items.show("item-123")
+
+if response.success?
+  item = response.data
+  puts "Item ID: #{item['id']}"
+  puts "Name: #{item['name']}"
+  puts "Amount: #{item['amount']}"
+  puts "Payment Type: #{item['payment_type']}"
+  puts "State: #{item['state']}"
+  puts "Buyer ID: #{item['buyer_id']}"
+  puts "Seller ID: #{item['seller_id']}"
+end
+```
+
+### Update Item
+
+Update an existing item's details.
+
+```ruby
+response = ZaiPayment.items.update(
+  "item-123",
+  name: "Updated Product Name",
+  description: "Updated product description",
+  amount: 12000,
+  buyer_url: "https://new-buyer.example.com",
+  tax_invoice: false
+)
+
+if response.success?
+  item = response.data
+  puts "Item updated: #{item['id']}"
+end
+```
+
+### Delete Item
+
+Delete an item by ID.
+
+```ruby
+response = ZaiPayment.items.delete("item-123")
+
+if response.success?
+  puts "Item deleted successfully"
+end
+```
+
+### Show Item Seller
+
+Get the seller (user) details for a specific item.
+
+```ruby
+response = ZaiPayment.items.show_seller("item-123")
+
+if response.success?
+  seller = response.data
+  puts "Seller: #{seller['first_name']} #{seller['last_name']}"
+  puts "Email: #{seller['email']}"
+  puts "Country: #{seller['country']}"
+end
+```
+
+### Show Item Buyer
+
+Get the buyer (user) details for a specific item.
+
+```ruby
+response = ZaiPayment.items.show_buyer("item-123")
+
+if response.success?
+  buyer = response.data
+  puts "Buyer: #{buyer['first_name']} #{buyer['last_name']}"
+  puts "Email: #{buyer['email']}"
+end
+```
+
+### Show Item Fees
+
+Get the fees associated with an item.
+
+```ruby
+response = ZaiPayment.items.show_fees("item-123")
+
+if response.success?
+  fees = response.data
+  
+  if fees && fees.any?
+    puts "Item has #{fees.length} fee(s):"
+    fees.each do |fee|
+      puts "  #{fee['name']}: $#{fee['amount'] / 100.0}"
+    end
+  end
+end
+```
+
+### Show Item Wire Details
+
+Get wire transfer details for an item (useful for bank transfers).
+
+```ruby
+response = ZaiPayment.items.show_wire_details("item-123")
+
+if response.success?
+  wire_details = response.data['wire_details']
+  
+  if wire_details
+    puts "Account Number: #{wire_details['account_number']}"
+    puts "Routing Number: #{wire_details['routing_number']}"
+    puts "Bank Name: #{wire_details['bank_name']}"
+  end
+end
+```
+
+### List Item Transactions
+
+Get all transactions associated with an item.
+
+```ruby
+# List transactions with default pagination
+response = ZaiPayment.items.list_transactions("item-123")
+
+if response.success?
+  transactions = response.data
+  
+  transactions.each do |transaction|
+    puts "Transaction #{transaction['id']}: #{transaction['state']}"
+    puts "  Amount: $#{transaction['amount'] / 100.0}"
+    puts "  Type: #{transaction['type']}"
+  end
+end
+
+# List with custom pagination
+response = ZaiPayment.items.list_transactions("item-123", limit: 50, offset: 100)
+```
+
+### List Item Batch Transactions
+
+Get all batch transactions associated with an item.
+
+```ruby
+response = ZaiPayment.items.list_batch_transactions("item-123")
+
+if response.success?
+  batch_transactions = response.data
+  
+  batch_transactions.each do |batch|
+    puts "Batch #{batch['id']}: #{batch['state']}"
+    puts "  Amount: $#{batch['amount'] / 100.0}"
+  end
+end
+
+# List with pagination
+response = ZaiPayment.items.list_batch_transactions("item-123", limit: 25, offset: 50)
+```
+
+### Show Item Status
+
+Get the current status of an item.
+
+```ruby
+response = ZaiPayment.items.show_status("item-123")
+
+if response.success?
+  status = response.data
+  puts "State: #{status['state']}"
+  puts "Payment State: #{status['payment_state']}"
+  puts "Disbursement State: #{status['disbursement_state']}" if status['disbursement_state']
+end
+```
+
+## Field Reference
+
+### Item Fields
+
+| Field | Type | Description | Required |
+|-------|------|-------------|----------|
+| `id` | String | Unique item ID (auto-generated if not provided) | Optional |
+| `name` | String | Name/title of the item | ✓ |
+| `amount` | Integer | Amount in cents (e.g., 10000 = $100.00) | ✓ |
+| `payment_type` | Integer | Payment type (1-7, default: 2) | ✓ |
+| `buyer_id` | String | Buyer user ID | ✓ |
+| `seller_id` | String | Seller user ID | ✓ |
+| `fee_ids` | Array | Array of fee IDs to apply | Optional |
+| `description` | String | Detailed description | Optional |
+| `currency` | String | Currency code (e.g., 'AUD', 'USD') | Optional |
+| `custom_descriptor` | String | Custom text for bank statements | Optional |
+| `buyer_url` | String | URL for buyer to access transaction | Optional |
+| `seller_url` | String | URL for seller to access transaction | Optional |
+| `tax_invoice` | Boolean | Whether to generate a tax invoice | Optional |
+
+### Payment Types
+
+When creating items, you can specify different payment types:
+
+| Type | Description |
+|------|-------------|
+| 1 | Direct Debit |
+| 2 | Credit Card (default) |
+| 3 | Bank Transfer |
+| 4 | Wallet |
+| 5 | BPay |
+| 6 | PayPal |
+| 7 | Other |
+
+Example:
+
+```ruby
+# Create item with bank transfer payment type
+response = ZaiPayment.items.create(
+  name: "Bank Transfer Payment",
+  amount: 30000,
+  payment_type: 3, # Bank Transfer
+  buyer_id: "buyer-123",
+  seller_id: "seller-456"
+)
+```
+
+## Item States
+
+Items go through various states during their lifecycle:
+
+- `pending` - Item created but not yet paid
+- `payment_pending` - Payment in progress
+- `payment_held` - Payment held (e.g., for review)
+- `payment_deposited` - Payment received and deposited
+- `work_completed` - Work/delivery completed
+- `completed` - Transaction completed successfully
+- `refunded` - Transaction refunded
+- `cancelled` - Transaction cancelled
+
+Check the item status using `show_status` method to track these state changes.
+
+## Error Handling
+
+The Item resource will raise validation errors for:
+
+- Missing required fields
+- Invalid amount (must be positive integer in cents)
+- Invalid payment type (must be 1-7)
+- Invalid item ID format
+- Item not found
+
+```ruby
+begin
+  response = ZaiPayment.items.create(
+    name: "Product",
+    amount: -100, # Invalid: negative amount
+    payment_type: 2,
+    buyer_id: "buyer-123",
+    seller_id: "seller-456"
+  )
+rescue ZaiPayment::Errors::ValidationError => e
+  puts "Validation error: #{e.message}"
+rescue ZaiPayment::Errors::NotFoundError => e
+  puts "Item not found: #{e.message}"
+rescue ZaiPayment::Errors::ApiError => e
+  puts "API error: #{e.message}"
+end
+```
+
+## Best Practices
+
+### 1. Use Meaningful Names and Descriptions
+
+Always provide clear, descriptive names and descriptions for items. This helps with:
+- Transaction tracking
+- Customer support
+- Financial reconciliation
+
+```ruby
+response = ZaiPayment.items.create(
+  name: "Order #12345 - Premium Widget",
+  description: "Premium widget with extended warranty - Customer: John Doe",
+  amount: 29900,
+  # ... other fields
+)
+```
+
+### 2. Track Custom IDs
+
+If you have your own order/transaction IDs, use the optional `id` field:
+
+```ruby
+response = ZaiPayment.items.create(
+  id: "order-#{your_order_id}",
+  name: "Order #{your_order_id}",
+  # ... other fields
+)
+```
+
+### 3. Set Buyer and Seller URLs
+
+Provide URLs so users can access transaction details on your platform:
+
+```ruby
+response = ZaiPayment.items.create(
+  buyer_url: "https://myapp.com/orders/#{order_id}",
+  seller_url: "https://myapp.com/sales/#{order_id}",
+  # ... other fields
+)
+```
+
+### 4. Monitor Transaction Status
+
+Regularly check item status to track payment and disbursement:
+
+```ruby
+status_response = ZaiPayment.items.show_status(item_id)
+puts "Payment: #{status_response.data['payment_state']}"
+puts "Disbursement: #{status_response.data['disbursement_state']}"
+```
+
+### 5. Handle Fees Properly
+
+If applying platform fees, create fee objects first and reference them:
+
+```ruby
+# Assume you've created fees with IDs: "fee-platform", "fee-service"
+response = ZaiPayment.items.create(
+  name: "Product Purchase",
+  amount: 50000,
+  fee_ids: ["fee-platform", "fee-service"],
+  # ... other fields
+)
+```
+
+## Response Structure
+
+### Successful Response
+
+```ruby
+response.success? # => true
+response.status   # => 200 or 201
+response.data     # => Item object hash
+response.meta     # => Pagination metadata (for list)
+```
+
+### Item Object Example
+
+```ruby
+{
+  "id" => "item-abc123",
+  "name" => "Product Purchase",
+  "amount" => 10000,
+  "payment_type" => 2,
+  "buyer_id" => "buyer-123",
+  "seller_id" => "seller-456",
+  "description" => "Purchase of product XYZ",
+  "currency" => "AUD",
+  "state" => "pending",
+  "payment_state" => "pending",
+  "buyer_url" => "https://buyer.example.com",
+  "seller_url" => "https://seller.example.com",
+  "tax_invoice" => true,
+  "created_at" => "2025-01-01T00:00:00Z",
+  "updated_at" => "2025-01-01T00:00:00Z"
+}
+```
+
+## Complete Workflow Example
+
+Here's a complete example of creating an item and tracking it through its lifecycle:
+
+```ruby
+require 'zai_payment'
+
+# Configure
+ZaiPayment.configure do |config|
+  config.client_id = ENV['ZAI_CLIENT_ID']
+  config.client_secret = ENV['ZAI_CLIENT_SECRET']
+  config.scope = ENV['ZAI_SCOPE']
+  config.environment = :prelive
+end
+
+items = ZaiPayment.items
+
+# 1. Create an item
+create_response = items.create(
+  name: "E-commerce Purchase - Order #12345",
+  amount: 50000, # $500.00
+  payment_type: 2, # Credit card
+  buyer_id: "buyer-abc123",
+  seller_id: "seller-xyz789",
+  description: "Online store purchase - Premium product bundle",
+  currency: "AUD",
+  buyer_url: "https://store.example.com/orders/12345",
+  seller_url: "https://seller.example.com/sales/12345",
+  tax_invoice: true
+)
+
+if create_response.success?
+  item_id = create_response.data['id']
+  puts "✓ Item created: #{item_id}"
+  
+  # 2. Get item details
+  show_response = items.show(item_id)
+  puts "✓ Item: #{show_response.data['name']}"
+  
+  # 3. Get seller details
+  seller_response = items.show_seller(item_id)
+  puts "✓ Seller: #{seller_response.data['email']}"
+  
+  # 4. Get buyer details
+  buyer_response = items.show_buyer(item_id)
+  puts "✓ Buyer: #{buyer_response.data['email']}"
+  
+  # 5. Check fees
+  fees_response = items.show_fees(item_id)
+  if fees_response.success? && fees_response.data&.any?
+    total_fees = fees_response.data.sum { |f| f['amount'] }
+    puts "✓ Total fees: $#{total_fees / 100.0}"
+  end
+  
+  # 6. Monitor status
+  status_response = items.show_status(item_id)
+  puts "✓ Payment state: #{status_response.data['payment_state']}"
+  
+  # 7. List transactions
+  txn_response = items.list_transactions(item_id)
+  puts "✓ Transactions: #{txn_response.data&.length || 0}"
+  
+  # 8. Update if needed
+  update_response = items.update(
+    item_id,
+    description: "Updated: Order #12345 - Payment confirmed"
+  )
+  puts "✓ Item updated" if update_response.success?
+else
+  puts "✗ Error: #{create_response.error_message}"
+end
+```
+
+## Integration with Rails
+
+### In a Controller
+
+```ruby
+class OrdersController < ApplicationController
+  def create
+    # Create users first (buyer and seller)
+    # ... user creation code ...
+    
+    # Create item
+    response = ZaiPayment.items.create(
+      name: "Order ##{@order.id}",
+      amount: (@order.total * 100).to_i, # Convert to cents
+      payment_type: 2,
+      buyer_id: @buyer_zai_id,
+      seller_id: @seller_zai_id,
+      description: @order.description,
+      buyer_url: order_url(@order),
+      seller_url: seller_order_url(@order),
+      tax_invoice: @order.requires_tax_invoice?
+    )
+    
+    if response.success?
+      @order.update(zai_item_id: response.data['id'])
+      redirect_to @order, notice: 'Order created successfully'
+    else
+      flash[:error] = "Payment error: #{response.error_message}"
+      render :new
+    end
+  end
+  
+  def show
+    # Get item status from Zai
+    if @order.zai_item_id
+      response = ZaiPayment.items.show_status(@order.zai_item_id)
+      @payment_status = response.data if response.success?
+    end
+  end
+end
+```
+
+### In a Background Job
+
+```ruby
+class CheckItemStatusJob < ApplicationJob
+  def perform(order_id)
+    order = Order.find(order_id)
+    
+    response = ZaiPayment.items.show_status(order.zai_item_id)
+    
+    if response.success?
+      status = response.data
+      
+      order.update(
+        payment_state: status['payment_state'],
+        disbursement_state: status['disbursement_state']
+      )
+      
+      # Send notifications based on state
+      if status['payment_state'] == 'completed'
+        OrderMailer.payment_completed(order).deliver_later
+      end
+    end
+  end
+end
+```
+
+## Testing
+
+The Item resource includes comprehensive test coverage. Run the tests with:
+
+```bash
+bundle exec rspec spec/zai_payment/resources/item_spec.rb
+```
+
+## See Also
+
+- [User Management Guide](users.md) - Managing buyers and sellers
+- [Webhook Documentation](webhooks.md) - Receiving item status updates
+- [Authentication Documentation](authentication.md) - OAuth2 setup
+- [Item Examples](../examples/items.md) - More code examples
+
+## External Resources
+
+- [Zai Items API Reference](https://developer.hellozai.com/reference/listitems)
+- [Zai Developer Portal](https://developer.hellozai.com/)
+- [Payment Types Documentation](https://developer.hellozai.com/docs/payment-types)
+
diff --git a/docs/README.md b/docs/readme.md
similarity index 100%
rename from docs/README.md
rename to docs/readme.md
diff --git a/docs/USER_ID_FIELD.md b/docs/user_id_field.md
similarity index 100%
rename from docs/USER_ID_FIELD.md
rename to docs/user_id_field.md
diff --git a/docs/USER_QUICK_REFERENCE.md b/docs/user_quick_reference.md
similarity index 95%
rename from docs/USER_QUICK_REFERENCE.md
rename to docs/user_quick_reference.md
index 89589b5..7a2cf5c 100644
--- a/docs/USER_QUICK_REFERENCE.md
+++ b/docs/user_quick_reference.md
@@ -47,7 +47,7 @@ response = ZaiPayment.users.create(
   first_name: 'Jane',
   last_name: 'Smith',
   country: 'AUS',
-  dob: '19900101',
+  dob: '01/01/1990',
   address_line1: '123 Main St',
   city: 'Sydney',
   state: 'NSW',
@@ -83,7 +83,7 @@ response = ZaiPayment.users.update(
 | first_name | String | ✓ |
 | last_name | String | ✓ |
 | country | String (ISO 3166-1 alpha-3) | ✓ |
-| dob | String (YYYYMMDD) | ✓ |
+| dob | String (DD/MM/YYYY) | ✓ |
 | address_line1 | String | ✓ |
 | city | String | ✓ |
 | state | String | ✓ |
@@ -106,9 +106,9 @@ country: 'GBR'  # United Kingdom
 country: 'CAN'  # Canada
 ```
 
-### Date of Birth (YYYYMMDD)
+### Date of Birth (DD/MM/YYYY)
 ```ruby
-dob: '19900101'  # January 1, 1990
+dob: '01/01/1990'  # January 1, 1990
 ```
 
 ## Error Handling
@@ -216,7 +216,7 @@ ruby examples/user_demo.rb
 
 ## Documentation Links
 
-- [Full User Guide](USERS.md)
+- [Full User Guide](users.md)
 - [Usage Examples](../examples/users.md)
 - [Zai: Payin User](https://developer.hellozai.com/docs/onboarding-a-pay-in-user)
 - [Zai: Payout User](https://developer.hellozai.com/docs/onboarding-a-pay-out-user)
@@ -224,7 +224,7 @@ ruby examples/user_demo.rb
 ## Support
 
 For issues or questions:
-1. Check the [User Management Guide](USERS.md)
+1. Check the [User Management Guide](users.md)
 2. Review [Examples](../examples/users.md)
 3. Visit [Zai Developer Portal](https://developer.hellozai.com/)
 
diff --git a/docs/USERS.md b/docs/users.md
similarity index 100%
rename from docs/USERS.md
rename to docs/users.md
diff --git a/docs/WEBHOOK_SECURITY_QUICKSTART.md b/docs/webhook_security_quickstart.md
similarity index 98%
rename from docs/WEBHOOK_SECURITY_QUICKSTART.md
rename to docs/webhook_security_quickstart.md
index 3cf5464..d91d4d8 100644
--- a/docs/WEBHOOK_SECURITY_QUICKSTART.md
+++ b/docs/webhook_security_quickstart.md
@@ -123,7 +123,7 @@ end
 
 ## 📚 Full Documentation
 
-- [Complete Setup Guide](WEBHOOKS.md#webhook-security-signature-verification)
+- [Complete Setup Guide](webhooks.md#webhook-security-signature-verification)
 - [More Examples](../examples/webhooks.md#webhook-security-complete-setup-guide)
 - [Zai Official Docs](https://developer.hellozai.com/docs/verify-webhook-signatures)
 
diff --git a/docs/WEBHOOK_SIGNATURE.md b/docs/webhook_signature.md
similarity index 100%
rename from docs/WEBHOOK_SIGNATURE.md
rename to docs/webhook_signature.md
diff --git a/docs/WEBHOOKS.md b/docs/webhooks.md
similarity index 100%
rename from docs/WEBHOOKS.md
rename to docs/webhooks.md
diff --git a/examples/items.md b/examples/items.md
new file mode 100644
index 0000000..97ad6fc
--- /dev/null
+++ b/examples/items.md
@@ -0,0 +1,598 @@
+# Zai Payment - Items Examples
+
+This document provides examples of how to use the Items resource in the Zai Payment gem.
+
+## Table of Contents
+
+- [Setup](#setup)
+- [Create Item](#create-item)
+- [List Items](#list-items)
+- [Show Item](#show-item)
+- [Update Item](#update-item)
+- [Delete Item](#delete-item)
+- [Show Item Seller](#show-item-seller)
+- [Show Item Buyer](#show-item-buyer)
+- [Show Item Fees](#show-item-fees)
+- [Show Item Wire Details](#show-item-wire-details)
+- [List Item Transactions](#list-item-transactions)
+- [List Item Batch Transactions](#list-item-batch-transactions)
+- [Show Item Status](#show-item-status)
+
+## Setup
+
+```ruby
+require 'zai_payment'
+
+# Configure the gem
+ZaiPayment.configure do |config|
+  config.client_id = 'your_client_id'
+  config.client_secret = 'your_client_secret'
+  config.scope = 'your_scope'
+  config.environment = :prelive # or :production
+end
+
+# Access the items resource
+items = ZaiPayment.items
+```
+
+## Create Item
+
+Create a new item (transaction/payment) between a buyer and a seller.
+
+```ruby
+# Create a basic item
+response = items.create(
+  name: "Product Purchase",
+  amount: 10000, # Amount in cents (100.00)
+  payment_type: 2, # Payment type (1-7, 2 is default)
+  buyer_id: "buyer-123",
+  seller_id: "seller-456"
+)
+
+if response.success?
+  item = response.data
+  puts "Item created: #{item['id']}"
+  puts "Name: #{item['name']}"
+  puts "Amount: #{item['amount']}"
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+### Create Item with Optional Fields
+
+```ruby
+response = items.create(
+  name: "Premium Product",
+  amount: 25000,
+  payment_type: 2,
+  buyer_id: "buyer-123",
+  seller_id: "seller-456",
+  description: "Purchase of premium product XYZ",
+  currency: "AUD",
+  fee_ids: ["fee-1", "fee-2"],
+  custom_descriptor: "MY STORE PURCHASE",
+  buyer_url: "https://buyer.example.com",
+  seller_url: "https://seller.example.com",
+  tax_invoice: true
+)
+
+if response.success?
+  item = response.data
+  puts "Item created with ID: #{item['id']}"
+  puts "Description: #{item['description']}"
+  puts "Tax Invoice: #{item['tax_invoice']}"
+end
+```
+
+### Create Item with Custom ID
+
+```ruby
+response = items.create(
+  id: "my-custom-item-#{Time.now.to_i}",
+  name: "Custom ID Product",
+  amount: 15000,
+  payment_type: 2,
+  buyer_id: "buyer-123",
+  seller_id: "seller-456"
+)
+
+if response.success?
+  item = response.data
+  puts "Item created with custom ID: #{item['id']}"
+end
+```
+
+## List Items
+
+Retrieve a list of all items with pagination and optional search/filtering.
+
+```ruby
+# List items with default pagination (10 items)
+response = items.list
+
+if response.success?
+  items_list = response.data
+  items_list.each do |item|
+    puts "Item ID: #{item['id']}, Name: #{item['name']}, Amount: #{item['amount']}"
+  end
+  
+  # Access metadata
+  meta = response.meta
+  puts "Total items: #{meta['total']}"
+  puts "Limit: #{meta['limit']}"
+  puts "Offset: #{meta['offset']}"
+end
+```
+
+### List Items with Custom Pagination
+
+```ruby
+# List 20 items starting from offset 40
+response = items.list(limit: 20, offset: 40)
+
+if response.success?
+  items_list = response.data
+  puts "Retrieved #{items_list.length} items"
+end
+```
+
+### Search Items by Description
+
+```ruby
+# Search for items with "product" in the description
+response = items.list(search: "product")
+
+if response.success?
+  items_list = response.data
+  puts "Found #{items_list.length} items matching 'product'"
+  items_list.each do |item|
+    puts "  - #{item['name']}: #{item['description']}"
+  end
+end
+```
+
+### Filter Items by Creation Date
+
+```ruby
+# Get items created in a specific date range
+response = items.list(
+  created_after: "2024-01-01T00:00:00Z",
+  created_before: "2024-12-31T23:59:59Z"
+)
+
+if response.success?
+  items_list = response.data
+  puts "Found #{items_list.length} items created in 2024"
+end
+```
+
+### Combine Search and Filters
+
+```ruby
+# Search with pagination and date filters
+response = items.list(
+  limit: 50,
+  offset: 0,
+  search: "premium",
+  created_after: "2024-01-01T00:00:00Z"
+)
+
+if response.success?
+  items_list = response.data
+  puts "Found #{items_list.length} premium items created after Jan 1, 2024"
+end
+```
+
+## Show Item
+
+Get details of a specific item by ID.
+
+```ruby
+response = items.show("item-123")
+
+if response.success?
+  item = response.data
+  puts "Item ID: #{item['id']}"
+  puts "Name: #{item['name']}"
+  puts "Amount: #{item['amount']}"
+  puts "Payment Type: #{item['payment_type']}"
+  puts "Buyer ID: #{item['buyer_id']}"
+  puts "Seller ID: #{item['seller_id']}"
+  puts "Description: #{item['description']}"
+  puts "State: #{item['state']}"
+  puts "Buyer URL: #{item['buyer_url']}" if item['buyer_url']
+  puts "Seller URL: #{item['seller_url']}" if item['seller_url']
+  puts "Tax Invoice: #{item['tax_invoice']}" unless item['tax_invoice'].nil?
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Update Item
+
+Update an existing item's details.
+
+```ruby
+response = items.update(
+  "item-123",
+  name: "Updated Product Name",
+  description: "Updated product description",
+  amount: 12000,
+  buyer_url: "https://new-buyer.example.com",
+  tax_invoice: false
+)
+
+if response.success?
+  item = response.data
+  puts "Item updated: #{item['id']}"
+  puts "New name: #{item['name']}"
+  puts "New amount: #{item['amount']}"
+  puts "Tax Invoice: #{item['tax_invoice']}"
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+### Update Item Seller or Buyer
+
+```ruby
+response = items.update(
+  "item-123",
+  seller_id: "new-seller-789",
+  buyer_id: "new-buyer-012"
+)
+
+if response.success?
+  puts "Item updated with new buyer and seller"
+end
+```
+
+## Delete Item
+
+Delete an item by ID.
+
+```ruby
+response = items.delete("item-123")
+
+if response.success?
+  puts "Item deleted successfully"
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Show Item Seller
+
+Get the seller (user) details for a specific item.
+
+```ruby
+response = items.show_seller("item-123")
+
+if response.success?
+  seller = response.data
+  puts "Seller ID: #{seller['id']}"
+  puts "Seller Email: #{seller['email']}"
+  puts "Seller Name: #{seller['first_name']} #{seller['last_name']}"
+  puts "Country: #{seller['country']}"
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Show Item Buyer
+
+Get the buyer (user) details for a specific item.
+
+```ruby
+response = items.show_buyer("item-123")
+
+if response.success?
+  buyer = response.data
+  puts "Buyer ID: #{buyer['id']}"
+  puts "Buyer Email: #{buyer['email']}"
+  puts "Buyer Name: #{buyer['first_name']} #{buyer['last_name']}"
+  puts "Country: #{buyer['country']}"
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Show Item Fees
+
+Get the fees associated with an item.
+
+```ruby
+response = items.show_fees("item-123")
+
+if response.success?
+  fees = response.data
+  
+  if fees && fees.any?
+    puts "Item has #{fees.length} fee(s):"
+    fees.each do |fee|
+      puts "  Fee ID: #{fee['id']}"
+      puts "  Name: #{fee['name']}"
+      puts "  Amount: #{fee['amount']}"
+      puts "  Fee Type: #{fee['fee_type']}"
+    end
+  else
+    puts "No fees associated with this item"
+  end
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Show Item Wire Details
+
+Get wire transfer details for an item.
+
+```ruby
+response = items.show_wire_details("item-123")
+
+if response.success?
+  wire_details = response.data['wire_details']
+  
+  if wire_details
+    puts "Wire Transfer Details:"
+    puts "  Account Number: #{wire_details['account_number']}"
+    puts "  Routing Number: #{wire_details['routing_number']}"
+    puts "  Bank Name: #{wire_details['bank_name']}"
+    puts "  Swift Code: #{wire_details['swift_code']}"
+  else
+    puts "No wire details available for this item"
+  end
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## List Item Transactions
+
+Get all transactions associated with an item.
+
+```ruby
+# List transactions with default pagination
+response = items.list_transactions("item-123")
+
+if response.success?
+  transactions = response.data
+  
+  if transactions && transactions.any?
+    puts "Item has #{transactions.length} transaction(s):"
+    transactions.each do |transaction|
+      puts "  Transaction ID: #{transaction['id']}"
+      puts "  Amount: #{transaction['amount']}"
+      puts "  State: #{transaction['state']}"
+      puts "  Type: #{transaction['type']}"
+      puts "  Created At: #{transaction['created_at']}"
+    end
+  else
+    puts "No transactions found for this item"
+  end
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+### List Item Transactions with Pagination
+
+```ruby
+# List 50 transactions starting from offset 100
+response = items.list_transactions("item-123", limit: 50, offset: 100)
+
+if response.success?
+  transactions = response.data
+  puts "Retrieved #{transactions.length} transactions"
+end
+```
+
+## List Item Batch Transactions
+
+Get all batch transactions associated with an item.
+
+```ruby
+response = items.list_batch_transactions("item-123")
+
+if response.success?
+  batch_transactions = response.data
+  
+  if batch_transactions && batch_transactions.any?
+    puts "Item has #{batch_transactions.length} batch transaction(s):"
+    batch_transactions.each do |batch|
+      puts "  Batch ID: #{batch['id']}"
+      puts "  Amount: #{batch['amount']}"
+      puts "  State: #{batch['state']}"
+      puts "  Created At: #{batch['created_at']}"
+    end
+  else
+    puts "No batch transactions found for this item"
+  end
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+### List Item Batch Transactions with Pagination
+
+```ruby
+# List 25 batch transactions starting from offset 50
+response = items.list_batch_transactions("item-123", limit: 25, offset: 50)
+
+if response.success?
+  batch_transactions = response.data
+  puts "Retrieved #{batch_transactions.length} batch transactions"
+end
+```
+
+## Show Item Status
+
+Get the current status of an item.
+
+```ruby
+response = items.show_status("item-123")
+
+if response.success?
+  item_status = response.data
+  puts "Item ID: #{item_status['id']}"
+  puts "State: #{item_status['state']}"
+  puts "Payment State: #{item_status['payment_state']}"
+  puts "Disbursement State: #{item_status['disbursement_state']}" if item_status['disbursement_state']
+  puts "Status Description: #{item_status['status_description']}" if item_status['status_description']
+else
+  puts "Error: #{response.error_message}"
+end
+```
+
+## Complete Workflow Example
+
+Here's a complete example of creating an item and performing various operations on it:
+
+```ruby
+require 'zai_payment'
+
+# Configure
+ZaiPayment.configure do |config|
+  config.client_id = ENV['ZAI_CLIENT_ID']
+  config.client_secret = ENV['ZAI_CLIENT_SECRET']
+  config.scope = ENV['ZAI_SCOPE']
+  config.environment = :prelive
+end
+
+items = ZaiPayment.items
+
+# 1. Create an item
+create_response = items.create(
+  name: "E-commerce Purchase",
+  amount: 50000, # $500.00
+  payment_type: 2,
+  buyer_id: "buyer-abc123",
+  seller_id: "seller-xyz789",
+  description: "Online store purchase - Order #12345",
+  currency: "AUD",
+  buyer_url: "https://buyer-portal.example.com",
+  seller_url: "https://seller-portal.example.com",
+  tax_invoice: true
+)
+
+if create_response.success?
+  item_id = create_response.data['id']
+  puts "✓ Item created: #{item_id}"
+  
+  # 2. Get item details
+  show_response = items.show(item_id)
+  if show_response.success?
+    puts "✓ Item retrieved: #{show_response.data['name']}"
+  end
+  
+  # 3. Get seller details
+  seller_response = items.show_seller(item_id)
+  if seller_response.success?
+    seller = seller_response.data
+    puts "✓ Seller: #{seller['email']}"
+  end
+  
+  # 4. Get buyer details
+  buyer_response = items.show_buyer(item_id)
+  if buyer_response.success?
+    buyer = buyer_response.data
+    puts "✓ Buyer: #{buyer['email']}"
+  end
+  
+  # 5. Check item status
+  status_response = items.show_status(item_id)
+  if status_response.success?
+    status = status_response.data
+    puts "✓ Item status: #{status['state']}"
+  end
+  
+  # 6. List transactions
+  transactions_response = items.list_transactions(item_id)
+  if transactions_response.success?
+    txn_count = transactions_response.data&.length || 0
+    puts "✓ Item has #{txn_count} transaction(s)"
+  end
+  
+  # 7. Update item if needed
+  update_response = items.update(
+    item_id,
+    description: "Updated: Online store purchase - Order #12345 (Confirmed)",
+    tax_invoice: true
+  )
+  if update_response.success?
+    puts "✓ Item updated successfully"
+  end
+else
+  puts "✗ Error creating item: #{create_response.error_message}"
+end
+```
+
+## Error Handling
+
+Always check the response status and handle errors appropriately:
+
+```ruby
+response = items.show("item-123")
+
+if response.success?
+  # Handle successful response
+  item = response.data
+  puts "Item: #{item['name']}"
+else
+  # Handle error
+  case response.status
+  when 404
+    puts "Item not found"
+  when 401
+    puts "Authentication failed - check your credentials"
+  when 422
+    puts "Validation error: #{response.error_message}"
+  else
+    puts "Error: #{response.error_message}"
+  end
+end
+```
+
+## Payment Types
+
+When creating items, you can specify different payment types:
+
+- **1**: Direct Debit
+- **2**: Credit Card (default)
+- **3**: Bank Transfer
+- **4**: Wallet
+- **5**: BPay
+- **6**: PayPal
+- **7**: Other
+
+Example:
+
+```ruby
+# Create item with bank transfer payment type
+response = items.create(
+  name: "Bank Transfer Payment",
+  amount: 30000,
+  payment_type: 3, # Bank Transfer
+  buyer_id: "buyer-123",
+  seller_id: "seller-456"
+)
+```
+
+## API Reference
+
+For more information about the Zai Items API, see:
+
+- [Create Item](https://developer.hellozai.com/reference/createitem)
+- [List Items](https://developer.hellozai.com/reference/listitems)
+- [Show Item](https://developer.hellozai.com/reference/showitem)
+- [Update Item](https://developer.hellozai.com/reference/updateitem)
+- [Delete Item](https://developer.hellozai.com/reference/deleteitem)
+- [Show Item Seller](https://developer.hellozai.com/reference/showitemseller)
+- [Show Item Buyer](https://developer.hellozai.com/reference/showitembuyer)
+- [Show Item Fees](https://developer.hellozai.com/reference/showitemfees)
+- [Show Item Wire Details](https://developer.hellozai.com/reference/showitemwiredetails)
+- [List Item Transactions](https://developer.hellozai.com/reference/listitemtransactions)
+- [List Item Batch Transactions](https://developer.hellozai.com/reference/listitembatchtransactions)
+- [Show Item Status](https://developer.hellozai.com/reference/showitemstatus)
+
diff --git a/examples/users.md b/examples/users.md
index 517e24c..9409097 100644
--- a/examples/users.md
+++ b/examples/users.md
@@ -32,6 +32,7 @@ Create a buyer with minimal required information.
 ```ruby
 # Create a basic payin user
 response = ZaiPayment.users.create(
+  user_type: 'payin',
   email: 'buyer@example.com',
   first_name: 'John',
   last_name: 'Doe',
@@ -43,6 +44,9 @@ if response.success?
   puts "Payin user created successfully!"
   puts "User ID: #{user['id']}"
   puts "Email: #{user['email']}"
+  
+  # Note: device_id and ip_address will be required later
+  # when creating an item and charging a card
 else
   puts "Failed to create user"
 end
@@ -55,6 +59,7 @@ Create a buyer with all recommended information for better fraud prevention.
 ```ruby
 response = ZaiPayment.users.create(
   # Required fields
+  user_type: 'payin',
   email: 'john.buyer@example.com',
   first_name: 'John',
   last_name: 'Doe',
@@ -67,15 +72,14 @@ response = ZaiPayment.users.create(
   state: 'NY',
   zip: '10001',
   mobile: '+1234567890',
-  dob: '15/01/1990',
-  
-  # For fraud prevention (required when charging)
-  device_id: 'device_abc123xyz',
-  ip_address: '192.168.1.1'
+  dob: '15/01/1990'
 )
 
 user = response.data
 puts "Complete payin user profile created: #{user['id']}"
+
+# Note: device_id and ip_address can be stored separately 
+# and will be required when creating an item and charging a card
 ```
 
 ### Example 3: Progressive Profile Building
@@ -85,6 +89,7 @@ Create a user quickly, then update with additional information later.
 ```ruby
 # Step 1: Quick user creation during signup
 response = ZaiPayment.users.create(
+  user_type: 'payin',
   email: 'quicksignup@example.com',
   first_name: 'Jane',
   last_name: 'Smith',
@@ -106,14 +111,9 @@ ZaiPayment.users.update(
 
 puts "User profile updated with shipping address"
 
-# Step 3: Add device info before payment
-ZaiPayment.users.update(
-  user_id,
-  device_id: 'device_xyz789',
-  ip_address: '203.0.113.42'
-)
-
-puts "Device information added for payment"
+# Note: device_id and ip_address should be captured during 
+# payment flow and will be required when creating an item
+# They are not stored in the user profile, but used at transaction time
 ```
 
 ## Payout User Examples
@@ -124,6 +124,9 @@ Create a seller who will receive payments. All required fields must be provided.
 
 ```ruby
 response = ZaiPayment.users.create(
+  # User type
+  user_type: 'payout',
+  
   # Required for payout users
   email: 'seller@example.com',
   first_name: 'Alice',
@@ -137,8 +140,7 @@ response = ZaiPayment.users.create(
   
   # Recommended
   mobile: '+14155551234',
-  government_number: '123456789',  # SSN or Tax ID
-  user_type: 'payout'
+  government_number: '123456789'  # SSN or Tax ID
 )
 
 seller = response.data
@@ -152,6 +154,7 @@ Create an Australian seller with appropriate details.
 
 ```ruby
 response = ZaiPayment.users.create(
+  user_type: 'payout',
   email: 'aussie.seller@example.com',
   first_name: 'Bruce',
   last_name: 'Williams',
@@ -165,8 +168,7 @@ response = ZaiPayment.users.create(
   zip: '2000',
   
   mobile: '+61298765432',
-  government_number: '123456789',  # TFN (Tax File Number)
-  user_type: 'payout'
+  government_number: '123456789'  # TFN (Tax File Number)
 )
 
 if response.success?
@@ -182,6 +184,7 @@ Create a UK-based seller.
 
 ```ruby
 response = ZaiPayment.users.create(
+  user_type: 'payout',
   email: 'uk.merchant@example.com',
   first_name: 'Oliver',
   last_name: 'Brown',
@@ -195,8 +198,7 @@ response = ZaiPayment.users.create(
   zip: 'SW1A 2AA',
   
   mobile: '+447700900123',
-  government_number: 'AB123456C',  # National Insurance Number
-  user_type: 'payout'
+  government_number: 'AB123456C'  # National Insurance Number
 )
 
 merchant = response.data
@@ -316,18 +318,21 @@ Create multiple users efficiently.
 ```ruby
 users_to_create = [
   {
+    user_type: 'payin',
     email: 'buyer1@example.com',
     first_name: 'Alice',
     last_name: 'Anderson',
     country: 'USA'
   },
   {
+    user_type: 'payin',
     email: 'buyer2@example.com',
     first_name: 'Bob',
     last_name: 'Brown',
     country: 'USA'
   },
   {
+    user_type: 'payout',
     email: 'seller1@example.com',
     first_name: 'Charlie',
     last_name: 'Chen',
@@ -336,8 +341,7 @@ users_to_create = [
     address_line1: '123 Test St',
     city: 'Sydney',
     state: 'NSW',
-    zip: '2000',
-    user_type: 'payout'
+    zip: '2000'
   }
 ]
 
@@ -549,6 +553,7 @@ end
 # Step 1: Create user during signup (minimal info)
 def create_initial_user(email:, name_parts:)
   ZaiPayment.users.create(
+    user_type: 'payin',  # or 'payout' based on your use case
     email: email,
     first_name: name_parts[:first],
     last_name: name_parts[:last],
@@ -592,32 +597,40 @@ Create a user representing a business entity with full company details.
 ```ruby
 # Example: Create a merchant user with company information
 response = ZaiPayment.users.create(
-  # Personal details
+  # User type
+  user_type: 'payout',
+  
+  # Personal details (required for payout users)
   email: 'john.director@example.com',
   first_name: 'John',
   last_name: 'Smith',
   country: 'AUS',
+  dob: '15/06/1985',
+  address_line1: '789 Business Ave',
+  city: 'Melbourne',
+  state: 'VIC',
+  zip: '3000',
   mobile: '+61412345678',
   
   # Business role
   authorized_signer_title: 'Director',
   
-  # Company details
+  # Company details (required fields for payout companies)
   company: {
     name: 'Smith Trading Co',
     legal_name: 'Smith Trading Company Pty Ltd',
     tax_number: '53004085616',  # ABN for Australian companies
     business_email: 'accounts@smithtrading.com',
     country: 'AUS',
-    charge_tax: true,  # GST registered
-    
-    # Business address
     address_line1: '123 Business Street',
-    address_line2: 'Suite 5',
     city: 'Melbourne',
     state: 'VIC',
     zip: '3000',
-    phone: '+61398765432'
+    phone: '+61398765432',
+    
+    # Optional fields
+    address_line2: 'Suite 5',
+    charge_tax: true  # GST registered
   }
 )
 
@@ -630,27 +643,24 @@ end
 
 ### Pattern 4: Enhanced Fraud Prevention
 
-Create users with additional verification data for enhanced security.
+Capture device information for payin users during payment flow.
 
 ```ruby
-# Example: Payin user with driver's license and IP tracking
+# Example: Payin user creation with recommended fields
 response = ZaiPayment.users.create(
   # Required fields
+  user_type: 'payin',
   email: 'secure.buyer@example.com',
   first_name: 'Sarah',
   last_name: 'Johnson',
   country: 'USA',
   
-  # Enhanced verification
+  # Recommended verification fields
   dob: '15/01/1990',
   government_number: '123-45-6789',  # SSN for US
   drivers_license_number: 'D1234567',
   drivers_license_state: 'CA',
   
-  # Fraud prevention
-  ip_address: '192.168.1.100',
-  device_id: 'device_abc123xyz',
-  
   # Contact and address
   mobile: '+14155551234',
   address_line1: '456 Market Street',
@@ -660,16 +670,22 @@ response = ZaiPayment.users.create(
   zip: '94103'
 )
 
-puts "Secure user created with enhanced verification"
+user_id = response.data['id']
+puts "User created with enhanced profile"
+
+# Note: device_id and ip_address should be captured during payment
+# and will be required when creating an item and charging a card.
+# They are typically obtained from your payment form or checkout page.
 ```
 
 ### Pattern 5: Custom Branding for Merchants
 
-Create a merchant user with custom branding for statements and payment pages.
+Create a payout merchant user with custom branding for statements and payment pages.
 
 ```ruby
 # Example: Merchant with custom branding
 response = ZaiPayment.users.create(
+  user_type: 'payout',
   email: 'merchant@brandedstore.com',
   first_name: 'Alex',
   last_name: 'Merchant',
@@ -677,17 +693,17 @@ response = ZaiPayment.users.create(
   mobile: '+61411222333',
   dob: '10/05/1985',
   
+  # Required address for payout users
+  address_line1: '789 Retail Plaza',
+  city: 'Brisbane',
+  state: 'QLD',
+  zip: '4000',
+  
   # Branding
   logo_url: 'https://example.com/logo.png',
   color_1: '#FF5733',  # Primary brand color
   color_2: '#C70039',  # Secondary brand color
-  custom_descriptor: 'BRANDED STORE',  # Shows on bank statements
-  
-  # Address
-  address_line1: '789 Retail Plaza',
-  city: 'Brisbane',
-  state: 'QLD',
-  zip: '4000'
+  custom_descriptor: 'BRANDED STORE'  # Shows on bank statements
 )
 
 merchant = response.data
@@ -697,11 +713,12 @@ puts "Custom descriptor: #{merchant['custom_descriptor']}"
 
 ### Pattern 6: AMEX Merchant Setup
 
-Create a merchant specifically configured for American Express transactions.
+Create a payout merchant specifically configured for American Express transactions.
 
 ```ruby
 # Example: AMEX merchant with required fields
 response = ZaiPayment.users.create(
+  user_type: 'payout',
   email: 'director@amexshop.com',
   first_name: 'Michael',
   last_name: 'Director',
@@ -712,25 +729,27 @@ response = ZaiPayment.users.create(
   # AMEX requirement: Must specify authorized signer title
   authorized_signer_title: 'Managing Director',
   
-  # Business details
+  # Required address for payout users
   address_line1: '100 Corporate Drive',
   city: 'Sydney',
   state: 'NSW',
   zip: '2000',
   
-  # Company for AMEX merchants
+  # Company for AMEX merchants (required fields for payout companies)
   company: {
     name: 'AMEX Shop',
     legal_name: 'AMEX Shop Pty Limited',
     tax_number: '51824753556',
     business_email: 'finance@amexshop.com',
     country: 'AUS',
-    charge_tax: true,
     address_line1: '100 Corporate Drive',
     city: 'Sydney',
     state: 'NSW',
     zip: '2000',
-    phone: '+61299887766'
+    phone: '+61299887766',
+    
+    # Optional
+    charge_tax: true
   }
 )
 
@@ -739,7 +758,7 @@ puts "AMEX-ready merchant created: #{response.data['id']}"
 
 ## See Also
 
-- [User Management Documentation](../docs/USERS.md)
+- [User Management Documentation](../docs/users.md)
 - [Webhook Examples](webhooks.md)
 - [Zai API Reference](https://developer.hellozai.com/reference)
 
diff --git a/IMPLEMENTATION.md b/implementation.md
similarity index 95%
rename from IMPLEMENTATION.md
rename to implementation.md
index 56161b8..75a2ef6 100644
--- a/IMPLEMENTATION.md
+++ b/implementation.md
@@ -28,7 +28,7 @@ A comprehensive User resource that provides CRUD operations for managing both pa
 - Country (ISO 3166-1 alpha-3 code, required)
 - Address details (line1, line2, city, state, zip)
 - Contact information (mobile, phone)
-- Date of birth (YYYYMMDD format)
+- Date of birth (DD/MM/YYYY format)
 - Government ID number
 - Device ID and IP address (for fraud prevention)
 - User type designation (payin/payout)
@@ -37,7 +37,7 @@ A comprehensive User resource that provides CRUD operations for managing both pa
 - Required field validation
 - Email format validation
 - Country code validation (3-letter ISO codes)
-- Date of birth format validation (YYYYMMDD)
+- Date of birth format validation (DD/MM/YYYY)
 - User type validation (payin/payout)
 
 ### 2. Client Updates (`lib/zai_payment/client.rb`)
@@ -83,7 +83,7 @@ A comprehensive User resource that provides CRUD operations for managing both pa
 
 ### 6. Documentation
 
-#### User Guide (`docs/USERS.md`)
+#### User Guide (`docs/users.md`)
 Comprehensive guide covering:
 - Overview of payin vs payout users
 - Required fields for each user type
@@ -110,7 +110,7 @@ Practical examples including:
 - RSpec integration tests
 - Common patterns with retry logic
 
-#### README Updates (`README.md`)
+#### README Updates (`readme.md`)
 - Added Users section with quick examples
 - Updated roadmap to mark Users as "Done"
 - Added documentation links
@@ -199,7 +199,7 @@ response = ZaiPayment.users.update(
 **Required:**
 - Email, first name, last name, country
 - Address, city, state, zip
-- Date of birth (YYYYMMDD format)
+- Date of birth (DD/MM/YYYY format)
 
 **Recommended:**
 - Mobile, government number
@@ -208,7 +208,7 @@ response = ZaiPayment.users.update(
 
 1. **Email**: Must be valid email format
 2. **Country**: Must be 3-letter ISO 3166-1 alpha-3 code (e.g., USA, AUS, GBR)
-3. **Date of Birth**: Must be YYYYMMDD format (e.g., 19900101)
+3. **Date of Birth**: Must be DD/MM/YYYY format (e.g., 19900101)
 4. **User Type**: Must be 'payin' or 'payout' (optional field)
 
 ## Error Handling
@@ -235,14 +235,14 @@ The implementation provides proper error handling for:
 ### Created Files:
 1. `/lib/zai_payment/resources/user.rb` - User resource class
 2. `/spec/zai_payment/resources/user_spec.rb` - Test suite
-3. `/docs/USERS.md` - User management guide
+3. `/docs/users.md` - User management guide
 4. `/examples/users.md` - Usage examples
 
 ### Modified Files:
 1. `/lib/zai_payment/client.rb` - Added endpoint support
 2. `/lib/zai_payment/response.rb` - Added users data handling
 3. `/lib/zai_payment.rb` - Integrated User resource
-4. `/README.md` - Added Users section and updated roadmap
+4. `/readme.md` - Added Users section and updated roadmap
 
 ## Code Quality
 
@@ -292,7 +292,7 @@ The implementation is complete and ready for use. Recommended next steps:
 ## Support
 
 For questions or issues:
-1. Check the documentation in `/docs/USERS.md`
+1. Check the documentation in `/docs/users.md`
 2. Review examples in `/examples/users.md`
 3. Run tests: `bundle exec rspec spec/zai_payment/resources/user_spec.rb`
 4. Refer to Zai Developer Portal: https://developer.hellozai.com/
diff --git a/IMPLEMENTATION_SUMMARY.md b/implementation_summary.md
similarity index 100%
rename from IMPLEMENTATION_SUMMARY.md
rename to implementation_summary.md
diff --git a/lib/zai_payment.rb b/lib/zai_payment.rb
index f7894e5..2ff151e 100644
--- a/lib/zai_payment.rb
+++ b/lib/zai_payment.rb
@@ -12,6 +12,7 @@
 require_relative 'zai_payment/response'
 require_relative 'zai_payment/resources/webhook'
 require_relative 'zai_payment/resources/user'
+require_relative 'zai_payment/resources/item'
 
 module ZaiPayment
   class << self
@@ -45,5 +46,10 @@ def webhooks
     def users
       @users ||= Resources::User.new(client: Client.new(base_endpoint: :core_base))
     end
+
+    # @return [ZaiPayment::Resources::Item] item resource instance
+    def items
+      @items ||= Resources::Item.new
+    end
   end
 end
diff --git a/lib/zai_payment/resources/item.rb b/lib/zai_payment/resources/item.rb
new file mode 100644
index 0000000..e412969
--- /dev/null
+++ b/lib/zai_payment/resources/item.rb
@@ -0,0 +1,363 @@
+# frozen_string_literal: true
+
+module ZaiPayment
+  module Resources
+    # Item resource for managing Zai items (transactions/payments)
+    #
+    # @see https://developer.hellozai.com/reference/listitems
+    class Item
+      attr_reader :client
+
+      # Map of attribute keys to API field names
+      FIELD_MAPPING = {
+        id: :id,
+        name: :name,
+        amount: :amount,
+        payment_type: :payment_type,
+        buyer_id: :buyer_id,
+        seller_id: :seller_id,
+        fee_ids: :fee_ids,
+        description: :description,
+        currency: :currency,
+        custom_descriptor: :custom_descriptor,
+        buyer_url: :buyer_url,
+        seller_url: :seller_url,
+        tax_invoice: :tax_invoice
+      }.freeze
+
+      def initialize(client: nil)
+        @client = client || Client.new
+      end
+
+      # List all items
+      #
+      # @param limit [Integer] number of records to return (default: 10, max: 200)
+      # @param offset [Integer] number of records to skip (default: 0)
+      # @param search [String] optional text value to search within item description
+      # @param created_before [String] optional ISO 8601 date/time to filter items created before
+      #   (e.g. '2020-02-27T23:54:59Z')
+      # @param created_after [String] optional ISO 8601 date/time to filter items created after
+      #   (e.g. '2020-02-27T23:54:59Z')
+      # @return [Response] the API response containing items array
+      #
+      # @example List all items
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.list
+      #   response.data # => [{"id" => "...", "name" => "..."}, ...]
+      #
+      # @example List items with search
+      #   response = items.list(search: "product")
+      #
+      # @example List items created within a date range
+      #   response = items.list(
+      #     created_after: "2024-01-01T00:00:00Z",
+      #     created_before: "2024-12-31T23:59:59Z"
+      #   )
+      #
+      # @see https://developer.hellozai.com/reference/listitems
+      def list(limit: 10, offset: 0, search: nil, created_before: nil, created_after: nil)
+        params = {
+          limit: limit,
+          offset: offset
+        }
+
+        params[:search] = search if search
+        params[:created_before] = created_before if created_before
+        params[:created_after] = created_after if created_after
+
+        client.get('/items', params: params)
+      end
+
+      # Get a specific item by ID
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing item details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show("item_id")
+      #   response.data # => {"items" => {"id" => "item_id", "name" => "...", ...}}
+      #
+      # @see https://developer.hellozai.com/reference/showitem
+      def show(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}")
+      end
+
+      # Create a new item
+      #
+      # @param attributes [Hash] item attributes
+      # @option attributes [String] :id Optional unique ID for the item
+      # @option attributes [String] :name (Required) Name of the item
+      # @option attributes [Integer] :amount (Required) Amount in cents
+      # @option attributes [String] :payment_type (Required) Payment type (1-7, default: 2)
+      # @option attributes [String] :buyer_id (Required) Buyer user ID
+      # @option attributes [String] :seller_id (Required) Seller user ID
+      # @option attributes [Array<String>] :fee_ids Optional array of fee IDs
+      # @option attributes [String] :description Optional description
+      # @option attributes [String] :currency Optional currency code (e.g., 'AUD')
+      # @option attributes [String] :custom_descriptor Optional custom descriptor
+      # @option attributes [String] :buyer_url Optional buyer URL
+      # @option attributes [String] :seller_url Optional seller URL
+      # @option attributes [Boolean] :tax_invoice Optional tax invoice flag
+      # @return [Response] the API response containing created item
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.create(
+      #     name: "Product Purchase",
+      #     amount: 10000,
+      #     payment_type: 2,
+      #     buyer_id: "buyer-123",
+      #     seller_id: "seller-456",
+      #     description: "Purchase of product XYZ"
+      #   )
+      #
+      # @see https://developer.hellozai.com/reference/createitem
+      def create(**attributes)
+        validate_create_attributes!(attributes)
+
+        body = build_item_body(attributes)
+        client.post('/items', body: body)
+      end
+
+      # Update an existing item
+      #
+      # @param item_id [String] the item ID
+      # @param attributes [Hash] item attributes to update
+      # @option attributes [String] :name Name of the item
+      # @option attributes [Integer] :amount Amount in cents
+      # @option attributes [String] :description Description
+      # @option attributes [String] :buyer_id Buyer user ID
+      # @option attributes [String] :seller_id Seller user ID
+      # @option attributes [Array<String>] :fee_ids Array of fee IDs
+      # @option attributes [String] :custom_descriptor Custom descriptor
+      # @option attributes [String] :buyer_url Buyer URL
+      # @option attributes [String] :seller_url Seller URL
+      # @option attributes [Boolean] :tax_invoice Tax invoice flag
+      # @return [Response] the API response containing updated item
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.update(
+      #     "item_id",
+      #     name: "Updated Product Name",
+      #     description: "Updated description"
+      #   )
+      #
+      # @see https://developer.hellozai.com/reference/updateitem
+      def update(item_id, **attributes)
+        validate_id!(item_id, 'item_id')
+
+        body = build_item_body(attributes)
+
+        raise Errors::ValidationError, 'At least one attribute must be provided for update' if body.empty?
+
+        client.patch("/items/#{item_id}", body: body)
+      end
+
+      # Delete an item
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.delete("item_id")
+      #
+      # @see https://developer.hellozai.com/reference/deleteitem
+      def delete(item_id)
+        validate_id!(item_id, 'item_id')
+        client.delete("/items/#{item_id}")
+      end
+
+      # Show item seller
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing seller details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show_seller("item_id")
+      #   response.data # => {"users" => {"id" => "...", "email" => "...", ...}}
+      #
+      # @see https://developer.hellozai.com/reference/showitemseller
+      def show_seller(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}/sellers")
+      end
+
+      # Show item buyer
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing buyer details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show_buyer("item_id")
+      #   response.data # => {"users" => {"id" => "...", "email" => "...", ...}}
+      #
+      # @see https://developer.hellozai.com/reference/showitembuyer
+      def show_buyer(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}/buyers")
+      end
+
+      # Show item fees
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing fees details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show_fees("item_id")
+      #   response.data # => {"fees" => [{"id" => "...", "amount" => "...", ...}]}
+      #
+      # @see https://developer.hellozai.com/reference/showitemfees
+      def show_fees(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}/fees")
+      end
+
+      # Show item wire details
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing wire transfer details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show_wire_details("item_id")
+      #   response.data # => {"items" => {"wire_details" => {...}}}
+      #
+      # @see https://developer.hellozai.com/reference/showitemwiredetails
+      def show_wire_details(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}/wire_details")
+      end
+
+      # List item transactions
+      #
+      # @param item_id [String] the item ID
+      # @param limit [Integer] number of records to return (default: 10)
+      # @param offset [Integer] number of records to skip (default: 0)
+      # @return [Response] the API response containing transactions array
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.list_transactions("item_id")
+      #   response.data # => {"transactions" => [{"id" => "...", "amount" => "...", ...}]}
+      #
+      # @see https://developer.hellozai.com/reference/listitemtransactions
+      def list_transactions(item_id, limit: 10, offset: 0)
+        validate_id!(item_id, 'item_id')
+
+        params = {
+          limit: limit,
+          offset: offset
+        }
+
+        client.get("/items/#{item_id}/transactions", params: params)
+      end
+
+      # List item batch transactions
+      #
+      # @param item_id [String] the item ID
+      # @param limit [Integer] number of records to return (default: 10)
+      # @param offset [Integer] number of records to skip (default: 0)
+      # @return [Response] the API response containing batch transactions array
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.list_batch_transactions("item_id")
+      #   response.data # => {"batch_transactions" => [{"id" => "...", ...}]}
+      #
+      # @see https://developer.hellozai.com/reference/listitembatchtransactions
+      def list_batch_transactions(item_id, limit: 10, offset: 0)
+        validate_id!(item_id, 'item_id')
+
+        params = {
+          limit: limit,
+          offset: offset
+        }
+
+        client.get("/items/#{item_id}/batch_transactions", params: params)
+      end
+
+      # Show item status
+      #
+      # @param item_id [String] the item ID
+      # @return [Response] the API response containing status details
+      #
+      # @example
+      #   items = ZaiPayment::Resources::Item.new
+      #   response = items.show_status("item_id")
+      #   response.data # => {"items" => {"state" => "...", ...}}
+      #
+      # @see https://developer.hellozai.com/reference/showitemstatus
+      def show_status(item_id)
+        validate_id!(item_id, 'item_id')
+        client.get("/items/#{item_id}/status")
+      end
+
+      private
+
+      def validate_id!(value, field_name)
+        return unless value.nil? || value.to_s.strip.empty?
+
+        raise Errors::ValidationError, "#{field_name} is required and cannot be blank"
+      end
+
+      def validate_presence!(value, field_name)
+        return unless value.nil? || value.to_s.strip.empty?
+
+        raise Errors::ValidationError, "#{field_name} is required and cannot be blank"
+      end
+
+      def validate_create_attributes!(attributes)
+        validate_required_attributes!(attributes)
+        validate_amount!(attributes[:amount]) if attributes[:amount]
+        validate_payment_type!(attributes[:payment_type]) if attributes[:payment_type]
+      end
+
+      def validate_required_attributes!(attributes)
+        required_fields = %i[name amount payment_type buyer_id seller_id]
+
+        missing_fields = required_fields.select do |field|
+          attributes[field].nil? || (attributes[field].respond_to?(:empty?) && attributes[field].to_s.strip.empty?)
+        end
+
+        return if missing_fields.empty?
+
+        raise Errors::ValidationError,
+              "Missing required fields: #{missing_fields.join(', ')}"
+      end
+
+      def validate_amount!(amount)
+        return if amount.is_a?(Integer) && amount.positive?
+
+        raise Errors::ValidationError, 'amount must be a positive integer (in cents)'
+      end
+
+      def validate_payment_type!(payment_type)
+        # Payment types: 1-7 (2 is default)
+        valid_types = %w[1 2 3 4 5 6 7]
+        return if valid_types.include?(payment_type.to_s)
+
+        raise Errors::ValidationError, 'payment_type must be between 1 and 7'
+      end
+
+      def build_item_body(attributes)
+        body = {}
+
+        attributes.each do |key, value|
+          next if value.nil? || (value.respond_to?(:empty?) && value.empty?)
+
+          api_field = FIELD_MAPPING[key]
+          body[api_field] = value if api_field
+        end
+
+        body
+      end
+    end
+  end
+end
diff --git a/lib/zai_payment/resources/user.rb b/lib/zai_payment/resources/user.rb
index 6297d95..7db5c40 100644
--- a/lib/zai_payment/resources/user.rb
+++ b/lib/zai_payment/resources/user.rb
@@ -107,19 +107,22 @@ def show(user_id)
       # @option attributes [String] :id Optional unique ID for the user. If not provided,
       #   Zai will generate one automatically. Cannot contain '.' character.
       #   Useful for mapping to your existing system's user IDs.
+      # @option attributes [String] :user_type User type ('payin' or 'payout').
+      #   This determines which fields are required.
       # @option attributes [String] :email (Required) user's email address
       # @option attributes [String] :first_name (Required) user's first name
       # @option attributes [String] :last_name (Required) user's last name
       # @option attributes [String] :country (Required) user's country code (ISO 3166-1 alpha-3)
-      # @option attributes [String] :user_type Optional user type ('payin' or 'payout')
+      # @option attributes [String] :address_line1 (Required for payout) user's address line 1
+      # @option attributes [String] :city (Required for payout) user's city
+      # @option attributes [String] :state (Required for payout) user's state
+      # @option attributes [String] :zip (Required for payout) user's postal/zip code
+      # @option attributes [String] :dob (Required for payout) user's date of birth (DD/MM/YYYY)
+      # @option attributes [String] :device_id device ID for fraud prevention (required when charging card)
+      # @option attributes [String] :ip_address IP address for fraud prevention (required when charging card)
+      # @option attributes [String] :address_line2 user's address line 2
       # @option attributes [String] :mobile user's mobile phone number (international format with '+')
       # @option attributes [String] :phone user's phone number
-      # @option attributes [String] :address_line1 user's address line 1
-      # @option attributes [String] :address_line2 user's address line 2
-      # @option attributes [String] :city user's city
-      # @option attributes [String] :state user's state
-      # @option attributes [String] :zip user's postal/zip code
-      # @option attributes [String] :dob user's date of birth (DD/MM/YYYY)
       # @option attributes [String] :government_number user's government ID number (SSN, TFN, etc.)
       # @option attributes [String] :drivers_license_number driving license number
       # @option attributes [String] :drivers_license_state state section of the user's driving license
@@ -129,13 +132,12 @@ def show(user_id)
       # @option attributes [String] :custom_descriptor custom descriptor for bundle direct debit statements
       # @option attributes [String] :authorized_signer_title job title for AMEX merchants (e.g., Director)
       # @option attributes [Hash] :company company details (creates a company for the user)
-      # @option attributes [String] :device_id device ID for fraud prevention
-      # @option attributes [String] :ip_address IP address for fraud prevention
       # @return [Response] the API response containing created user
       #
       # @example Create a payin user (buyer) with auto-generated ID
       #   users = ZaiPayment::Resources::User.new
       #   response = users.create(
+      #     user_type: "payin",
       #     email: "buyer@example.com",
       #     first_name: "John",
       #     last_name: "Doe",
@@ -146,25 +148,29 @@ def show(user_id)
       #     state: "NY",
       #     zip: "10001"
       #   )
+      #   # Note: device_id and ip_address are not required at user creation,
+      #   # but will be required when creating an item and charging a card
       #
       # @example Create a payin user with custom ID
       #   users = ZaiPayment::Resources::User.new
       #   response = users.create(
       #     id: "buyer-#{your_user_id}",
+      #     user_type: "payin",
       #     email: "buyer@example.com",
       #     first_name: "John",
       #     last_name: "Doe",
       #     country: "USA"
       #   )
       #
-      # @example Create a payout user (seller/merchant)
+      # @example Create a payout user (seller/merchant) - individual
       #   users = ZaiPayment::Resources::User.new
       #   response = users.create(
+      #     user_type: "payout",
       #     email: "seller@example.com",
       #     first_name: "Jane",
       #     last_name: "Smith",
       #     country: "AUS",
-      #     dob: "19900101",
+      #     dob: "01/01/1990",
       #     address_line1: "456 Market St",
       #     city: "Sydney",
       #     state: "NSW",
@@ -172,13 +178,19 @@ def show(user_id)
       #     mobile: "+61412345678"
       #   )
       #
-      # @example Create a user with company details
+      # @example Create a payout user with company details
       #   users = ZaiPayment::Resources::User.new
       #   response = users.create(
+      #     user_type: "payout",
       #     email: "business@example.com",
       #     first_name: "John",
       #     last_name: "Doe",
       #     country: "AUS",
+      #     dob: "15/06/1985",
+      #     address_line1: "789 Business Ave",
+      #     city: "Melbourne",
+      #     state: "VIC",
+      #     zip: "3000",
       #     mobile: "+61412345678",
       #     authorized_signer_title: "Director",
       #     company: {
@@ -186,13 +198,12 @@ def show(user_id)
       #       legal_name: "ABC Pty Ltd",
       #       tax_number: "123456789",
       #       business_email: "admin@abc.com",
-      #       country: "AUS",
-      #       charge_tax: true,
       #       address_line1: "123 Business St",
       #       city: "Melbourne",
       #       state: "VIC",
       #       zip: "3000",
-      #       phone: "+61398765432"
+      #       phone: "+61398765432",
+      #       country: "AUS"
       #     }
       #   )
       #
@@ -274,12 +285,23 @@ def validate_create_attributes!(attributes) # rubocop:disable Metrics/AbcSize
         validate_country!(attributes[:country])
         validate_dob!(attributes[:dob]) if attributes[:dob]
         validate_user_id!(attributes[:id]) if attributes[:id]
-        validate_company!(attributes[:company]) if attributes[:company]
+        validate_company!(attributes[:company], attributes[:user_type]) if attributes[:company]
       end
 
       def validate_required_attributes!(attributes)
+        # Base required fields for all users
         required_fields = %i[email first_name last_name country]
 
+        # Additional required fields for payout users
+        user_type = attributes[:user_type]&.to_s&.downcase
+        if user_type == USER_TYPE_PAYOUT
+          # For payout users, these fields become required
+          required_fields += %i[address_line1 city state zip dob]
+        end
+
+        # NOTE: device_id and ip_address are NOT required at user creation for payin users.
+        # They are only required later when an item is created and a card is charged.
+
         missing_fields = required_fields.select do |field|
           attributes[field].nil? || attributes[field].to_s.strip.empty?
         end
@@ -329,15 +351,11 @@ def validate_user_id!(user_id)
         raise Errors::ValidationError, 'id cannot be blank if provided'
       end
 
-      def validate_company!(company)
+      def validate_company!(company, user_type = nil)
         return unless company.is_a?(Hash)
 
-        # Required company fields
-        required_company_fields = %i[name legal_name tax_number business_email country]
-
-        missing_fields = required_company_fields.select do |field|
-          company[field].nil? || company[field].to_s.strip.empty?
-        end
+        required_fields = required_company_fields(user_type)
+        missing_fields = find_missing_company_fields(company, required_fields)
 
         return if missing_fields.empty?
 
@@ -345,6 +363,26 @@ def validate_company!(company)
               "Company is missing required fields: #{missing_fields.join(', ')}"
       end
 
+      def required_company_fields(user_type)
+        base_fields = %i[name legal_name tax_number business_email]
+        additional_fields = payout_company?(user_type) ? payout_company_fields : %i[country]
+        base_fields + additional_fields
+      end
+
+      def payout_company?(user_type)
+        user_type&.to_s&.downcase == USER_TYPE_PAYOUT
+      end
+
+      def payout_company_fields
+        %i[address_line1 city state zip phone country]
+      end
+
+      def find_missing_company_fields(company, required_fields)
+        required_fields.select do |field|
+          company[field].nil? || company[field].to_s.strip.empty?
+        end
+      end
+
       def build_user_body(attributes) # rubocop:disable Metrics/CyclomaticComplexity
         body = {}
 
diff --git a/lib/zai_payment/response.rb b/lib/zai_payment/response.rb
index 7ff228d..0bdd650 100644
--- a/lib/zai_payment/response.rb
+++ b/lib/zai_payment/response.rb
@@ -30,9 +30,14 @@ def server_error?
     end
 
     # Get the data from the response body
+    # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity
     def data
-      body.is_a?(Hash) ? body['webhooks'] || body['users'] || body : body
+      return body unless body.is_a?(Hash)
+
+      body['webhooks'] || body['users'] || body['items'] || body['fees'] ||
+        body['transactions'] || body['batch_transactions'] || body
     end
+    # rubocop:enable Metrics/AbcSize, Metrics/CyclomaticComplexity
 
     # Get pagination or metadata info
     def meta
diff --git a/lib/zai_payment/version.rb b/lib/zai_payment/version.rb
index ae7e706..e7722e2 100644
--- a/lib/zai_payment/version.rb
+++ b/lib/zai_payment/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module ZaiPayment
-  VERSION = '1.3.2'
+  VERSION = '2.0.0'
 end
diff --git a/README.md b/readme.md
similarity index 77%
rename from README.md
rename to readme.md
index e92f194..0d1d5d2 100644
--- a/README.md
+++ b/readme.md
@@ -1,7 +1,7 @@
 # Zai Payment Ruby Library
 
 ![GitHub License](https://img.shields.io/github/license/Sentia/zai-payment)
-[![Code of Conduct](https://img.shields.io/badge/code%20of%20conduct-MIT-blue.svg)](./CODE_OF_CONDUCT.md)
+[![Code of Conduct](https://img.shields.io/badge/code%20of%20conduct-MIT-blue.svg)](./code_of_conduct.md)
 [![Gem Version](https://img.shields.io/gem/v/zai_payment.svg)](https://rubygems.org/gems/zai_payment)
 [![GitHub release](https://img.shields.io/github/release/Sentia/zai-payment.svg)](https://github.com/Sentia/zai-payment/releases)
 [![Gem](https://img.shields.io/gem/dt/zai_payment.svg)](https://rubygems.org/gems/zai_payment)
@@ -9,7 +9,7 @@
 ![Endpoint Badge](https://img.shields.io/endpoint?url=https%3A%2F%2Fraw.githubusercontent.com%2FSentia%2Fzai-payment%2Fmain%2Fbadges%2Fcoverage.json)
 ![GitHub top language](https://img.shields.io/github/languages/top/Sentia/zai-payment)
 [![Documentation](https://img.shields.io/badge/docs-rubydoc.info-blue.svg)](https://rubydoc.info/gems/zai_payment?refresh=true)
-[![Contributing](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)](./CONTRIBUTING.md)
+[![Contributing](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)](./contributing.md)
 
 A lightweight and extensible Ruby client for the **Zai (AssemblyPay)** API — starting with secure OAuth2 authentication, and ready for Payments, Virtual Accounts, Webhooks, and more.
 
@@ -20,6 +20,7 @@ A lightweight and extensible Ruby client for the **Zai (AssemblyPay)** API — s
 - 🔐 **OAuth2 Authentication** - Client Credentials flow with automatic token management  
 - 🧠 **Smart Token Caching** - Auto-refresh before expiration, thread-safe storage  
 - 👥 **User Management** - Create and manage payin (buyers) & payout (sellers) users  
+- 📦 **Item Management** - Full CRUD for transactions/payments between buyers and sellers  
 - 🪝 **Webhooks** - Full CRUD + secure signature verification (HMAC SHA256)  
 - ⚙️ **Environment-Aware** - Seamless Pre-live / Production switching  
 - 🧱 **Modular & Extensible** - Clean resource-based architecture  
@@ -77,7 +78,7 @@ token = token_provider.bearer_token
 
 The gem handles OAuth2 Client Credentials flow automatically - tokens are cached and refreshed before expiration.
 
-📖 **<a href="docs/AUTHENTICATION.md">Complete Authentication Guide</a>** - Two approaches, examples, and best practices
+📖 **<a href="docs/authentication.md">Complete Authentication Guide</a>** - Two approaches, examples, and best practices
 
 ### Users
 
@@ -99,7 +100,7 @@ response = ZaiPayment.users.create(
   first_name: 'Jane',
   last_name: 'Smith',
   country: 'AUS',
-  dob: '19900101',
+  dob: '01/01/1990',
   address_line1: '456 Market St',
   city: 'Sydney',
   state: 'NSW',
@@ -135,11 +136,53 @@ response = ZaiPayment.users.update('user_id', mobile: '+9876543210')
 ```
 
 **📚 Documentation:**
-- 📖 [User Management Guide](docs/USERS.md) - Complete guide for payin and payout users
+- 📖 [User Management Guide](docs/users.md) - Complete guide for payin and payout users
 - 💡 [User Examples](examples/users.md) - Real-world usage patterns and Rails integration
 - 🔗 [Zai: Onboarding a Payin User](https://developer.hellozai.com/docs/onboarding-a-pay-in-user)
 - 🔗 [Zai: Onboarding a Payout User](https://developer.hellozai.com/docs/onboarding-a-pay-out-user)
 
+### Items
+
+Manage transactions/payments between buyers and sellers:
+
+```ruby
+# Create an item
+response = ZaiPayment.items.create(
+  name: "Product Purchase",
+  amount: 10000, # Amount in cents ($100.00)
+  payment_type: 2, # Credit card
+  buyer_id: "buyer-123",
+  seller_id: "seller-456",
+  description: "Purchase of premium product",
+  currency: "AUD",
+  tax_invoice: true
+)
+
+# List items
+response = ZaiPayment.items.list(limit: 20, offset: 0)
+
+# Get item details
+response = ZaiPayment.items.show('item_id')
+
+# Update item
+response = ZaiPayment.items.update('item_id', name: 'Updated Name')
+
+# Get item status
+response = ZaiPayment.items.show_status('item_id')
+
+# Get buyer/seller details
+response = ZaiPayment.items.show_buyer('item_id')
+response = ZaiPayment.items.show_seller('item_id')
+
+# List transactions
+response = ZaiPayment.items.list_transactions('item_id')
+```
+
+**📚 Documentation:**
+- 📖 [Item Management Guide](docs/items.md) - Complete guide for creating and managing items
+- 💡 [Item Examples](examples/items.md) - Real-world usage patterns and complete workflows
+- 🔗 [Zai: Items API Reference](https://developer.hellozai.com/reference/listitems)
+
 ### Webhooks
 
 Manage webhook endpoints:
@@ -163,9 +206,9 @@ ZaiPayment.webhooks.create_secret_key(secret_key: secret_key)
 
 **📚 Documentation:**
 - 📖 [Webhook Examples & Complete Guide](examples/webhooks.md) - Full CRUD operations and patterns
-- 🔒 [Security Quick Start](docs/WEBHOOK_SECURITY_QUICKSTART.md) - 5-minute webhook security setup
-- 🏗️ [Architecture & Implementation](docs/WEBHOOKS.md) - Detailed technical documentation
-- 🔐 [Signature Verification Details](docs/WEBHOOK_SIGNATURE.md) - Security implementation specs
+- 🔒 [Security Quick Start](docs/webhook_security_quickstart.md) - 5-minute webhook security setup
+- 🏗️ [Architecture & Implementation](docs/webhooks.md) - Detailed technical documentation
+- 🔐 [Signature Verification Details](docs/webhook_signature.md) - Security implementation specs
 
 ### Error Handling
 
@@ -199,6 +242,7 @@ end
 | ✅ Authentication                | OAuth2 Client Credentials flow    | Done           |
 | ✅ Webhooks                     | CRUD for webhook endpoints        | Done           |
 | ✅ Users                        | Manage PayIn / PayOut users       | Done           |
+| ✅ Items                        | Transactions/payments (CRUD)      | Done           |
 | 💳 Payments                     | Single and recurring payments     | 🚧 In progress |
 | 🏦 Virtual Accounts (VA / PIPU) | Manage virtual accounts & PayTo   | ⏳ Planned      |
 | 💼 Wallets                      | Create and manage wallet accounts | ⏳ Planned      |
@@ -236,12 +280,12 @@ This will load the gem and all its dependencies, allowing you to experiment with
 ## 🧾 Versioning
 This gem follows [Semantic Versioning](https://semver.org).
 
-See [CHANGELOG.md](./CHANGELOG.md) for release history.
+See [changelog.md](./changelog.md) for release history.
 
 
 ## 🤝 Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/Sentia/zai-payment. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/Sentia/zai-payment/blob/main/CODE_OF_CONDUCT.md).
+Bug reports and pull requests are welcome on GitHub at https://github.com/Sentia/zai-payment. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/Sentia/zai-payment/blob/main/code_of_conduct.md).
 
 ## 🪪 License
 
@@ -249,27 +293,29 @@ The gem is available as open source under the terms of the [MIT License](https:/
 
 ## Code of Conduct
 
-Everyone interacting in the ZaiPayment project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/Sentia/zai-payment/blob/main/CODE_OF_CONDUCT.md).
+Everyone interacting in the ZaiPayment project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/Sentia/zai-payment/blob/main/code_of_conduct.md).
 
 ## 📚 Documentation
 
 ### Getting Started
-- [**Authentication Guide**](docs/AUTHENTICATION.md) - Two approaches to getting tokens, automatic management
-- [**User Management Guide**](docs/USERS.md) - Managing payin and payout users
+- [**Authentication Guide**](docs/authentication.md) - Two approaches to getting tokens, automatic management
+- [**User Management Guide**](docs/users.md) - Managing payin and payout users
+- [**Item Management Guide**](docs/items.md) - Creating and managing transactions/payments
 - [**Webhook Examples**](examples/webhooks.md) - Complete webhook usage guide
-- [**Documentation Index**](docs/README.md) - Full documentation navigation
+- [**Documentation Index**](docs/readme.md) - Full documentation navigation
 
 ### Examples & Patterns
 - [User Examples](examples/users.md) - Real-world user management patterns
+- [Item Examples](examples/items.md) - Transaction and payment workflows
 - [Webhook Examples](examples/webhooks.md) - Webhook integration patterns
 
 ### Technical Guides
-- [Webhook Architecture](docs/WEBHOOKS.md) - Technical implementation details
-- [Architecture Overview](docs/ARCHITECTURE.md) - System architecture and design
+- [Webhook Architecture](docs/webhooks.md) - Technical implementation details
+- [Architecture Overview](docs/architecture.md) - System architecture and design
 
 ### Security
-- [Webhook Security Quick Start](docs/WEBHOOK_SECURITY_QUICKSTART.md) - 5-minute setup guide
-- [Signature Verification](docs/WEBHOOK_SIGNATURE.md) - Implementation details
+- [Webhook Security Quick Start](docs/webhook_security_quickstart.md) - 5-minute setup guide
+- [Signature Verification](docs/webhook_signature.md) - Implementation details
 
 ### External Resources
 - [Zai Developer Portal](https://developer.hellozai.com/)
diff --git a/spec/zai_payment/resources/item_spec.rb b/spec/zai_payment/resources/item_spec.rb
new file mode 100644
index 0000000..4e1d16a
--- /dev/null
+++ b/spec/zai_payment/resources/item_spec.rb
@@ -0,0 +1,670 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ZaiPayment::Resources::Item do
+  let(:stubs) { Faraday::Adapter::Test::Stubs.new }
+  let(:item_resource) { described_class.new(client: test_client) }
+
+  let(:test_client) do
+    config = ZaiPayment::Config.new.tap do |c|
+      c.environment = :prelive
+      c.client_id = 'test_client_id'
+      c.client_secret = 'test_client_secret'
+      c.scope = 'test_scope'
+    end
+
+    token_provider = instance_double(ZaiPayment::Auth::TokenProvider, bearer_token: 'Bearer test_token')
+    client = ZaiPayment::Client.new(config: config, token_provider: token_provider)
+
+    test_connection = Faraday.new do |faraday|
+      faraday.request :json
+      faraday.response :json, content_type: /\bjson$/
+      faraday.adapter :test, stubs
+    end
+
+    allow(client).to receive(:connection).and_return(test_connection)
+    client
+  end
+
+  after do
+    stubs.verify_stubbed_calls
+  end
+
+  describe '#list' do
+    context 'when successful' do
+      before do
+        stubs.get('/items') do |env|
+          [200, { 'Content-Type' => 'application/json' }, item_list_data] if env.params['limit'] == '10'
+        end
+      end
+
+      let(:item_list_data) do
+        {
+          'items' => [
+            {
+              'id' => 'item_1',
+              'name' => 'Product A',
+              'amount' => 10_000,
+              'payment_type' => 2,
+              'buyer_id' => 'buyer_123',
+              'seller_id' => 'seller_456'
+            },
+            {
+              'id' => 'item_2',
+              'name' => 'Product B',
+              'amount' => 20_000,
+              'payment_type' => 2,
+              'buyer_id' => 'buyer_789',
+              'seller_id' => 'seller_012'
+            }
+          ],
+          'meta' => {
+            'total' => 2,
+            'limit' => 10,
+            'offset' => 0
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.list
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the item data' do
+        response = item_resource.list
+        expect(response.data).to eq(item_list_data['items'])
+      end
+
+      it 'returns the metadata' do
+        response = item_resource.list
+        expect(response.meta).to eq(item_list_data['meta'])
+      end
+    end
+
+    context 'with custom pagination' do
+      before do
+        stubs.get('/items') do |env|
+          [200, { 'Content-Type' => 'application/json' }, item_list_data] if env.params['limit'] == '20'
+        end
+      end
+
+      let(:item_list_data) do
+        {
+          'items' => [],
+          'meta' => { 'total' => 0, 'limit' => 20, 'offset' => 10 }
+        }
+      end
+
+      it 'accepts custom limit and offset' do
+        response = item_resource.list(limit: 20, offset: 10)
+        expect(response.success?).to be true
+      end
+    end
+
+    context 'with search parameter' do
+      before do
+        stubs.get('/items') do |env|
+          [200, { 'Content-Type' => 'application/json' }, search_results] if env.params['search'] == 'product'
+        end
+      end
+
+      let(:search_results) do
+        {
+          'items' => [
+            {
+              'id' => 'item_1',
+              'name' => 'Product A',
+              'description' => 'Premium product',
+              'amount' => 10_000
+            }
+          ],
+          'meta' => { 'total' => 1, 'limit' => 10, 'offset' => 0 }
+        }
+      end
+
+      it 'accepts search parameter' do
+        response = item_resource.list(search: 'product')
+        expect(response.success?).to be true
+        expect(response.data.length).to eq(1)
+      end
+    end
+
+    context 'with date filters' do
+      before do
+        stubs.get('/items') do |env|
+          if env.params['created_after'] && env.params['created_before']
+            [200, { 'Content-Type' => 'application/json' }, filtered_results]
+          end
+        end
+      end
+
+      let(:filtered_results) do
+        {
+          'items' => [
+            {
+              'id' => 'item_1',
+              'name' => 'Recent Item',
+              'amount' => 10_000,
+              'created_at' => '2024-06-15T10:00:00Z'
+            }
+          ],
+          'meta' => { 'total' => 1, 'limit' => 10, 'offset' => 0 }
+        }
+      end
+
+      it 'accepts created_after and created_before parameters' do
+        response = item_resource.list(
+          created_after: '2024-01-01T00:00:00Z',
+          created_before: '2024-12-31T23:59:59Z'
+        )
+        expect(response.success?).to be true
+        expect(response.data.length).to eq(1)
+      end
+    end
+  end
+
+  describe '#show' do
+    context 'when item exists' do
+      before do
+        stubs.get('/items/item_123') do
+          [200, { 'Content-Type' => 'application/json' }, item_detail]
+        end
+      end
+
+      let(:item_detail) do
+        {
+          'items' => {
+            'id' => 'item_123',
+            'name' => 'Test Product',
+            'amount' => 15_000,
+            'payment_type' => 2,
+            'buyer_id' => 'buyer_123',
+            'seller_id' => 'seller_456',
+            'description' => 'Test description'
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the item details' do
+        response = item_resource.show('item_123')
+        expect(response.data['id']).to eq('item_123')
+        expect(response.data['name']).to eq('Test Product')
+      end
+    end
+
+    context 'when item does not exist' do
+      before do
+        stubs.get('/items/item_123') do
+          [404, { 'Content-Type' => 'application/json' }, { 'error' => 'Item not found' }]
+        end
+      end
+
+      it 'raises a NotFoundError' do
+        expect { item_resource.show('item_123') }.to raise_error(ZaiPayment::Errors::NotFoundError)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError for empty string' do
+        expect { item_resource.show('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+
+      it 'raises a ValidationError for nil' do
+        expect { item_resource.show(nil) }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#create' do
+    let(:base_params) do
+      {
+        name: 'Test Product',
+        amount: 10_000,
+        payment_type: 2,
+        buyer_id: 'buyer_123',
+        seller_id: 'seller_456'
+      }
+    end
+
+    context 'when creating an item successfully' do
+      let(:created_response) do
+        {
+          'items' => base_params.transform_keys(&:to_s).merge('id' => 'item_new')
+        }
+      end
+
+      before do
+        stubs.post('/items') do |env|
+          body = JSON.parse(env.body)
+          [201, { 'Content-Type' => 'application/json' }, created_response] if body['name'] == 'Test Product'
+        end
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.create(**base_params)
+        expect(response).to be_a(ZaiPayment::Response)
+      end
+
+      it 'returns the created item with correct data' do
+        response = item_resource.create(**base_params)
+        expect(response.data['id']).to eq('item_new')
+        expect(response.data['name']).to eq(base_params[:name])
+        expect(response.data['amount']).to eq(base_params[:amount])
+      end
+    end
+
+    context 'when required fields are missing' do
+      it 'raises a ValidationError for missing name' do
+        params = base_params.except(:name)
+        expect { item_resource.create(**params) }.to raise_error(
+          ZaiPayment::Errors::ValidationError, /Missing required fields:.*name/
+        )
+      end
+
+      it 'raises a ValidationError for missing amount' do
+        params = base_params.except(:amount)
+        expect { item_resource.create(**params) }.to raise_error(
+          ZaiPayment::Errors::ValidationError, /Missing required fields:.*amount/
+        )
+      end
+
+      it 'raises a ValidationError for missing payment_type' do
+        params = base_params.except(:payment_type)
+        expect { item_resource.create(**params) }.to raise_error(
+          ZaiPayment::Errors::ValidationError, /Missing required fields:.*payment_type/
+        )
+      end
+
+      it 'raises a ValidationError for missing buyer_id' do
+        params = base_params.except(:buyer_id)
+        expect { item_resource.create(**params) }.to raise_error(
+          ZaiPayment::Errors::ValidationError, /Missing required fields:.*buyer_id/
+        )
+      end
+
+      it 'raises a ValidationError for missing seller_id' do
+        params = base_params.except(:seller_id)
+        expect { item_resource.create(**params) }.to raise_error(
+          ZaiPayment::Errors::ValidationError, /Missing required fields:.*seller_id/
+        )
+      end
+    end
+
+    context 'when amount is invalid' do
+      it 'raises a ValidationError for negative amount' do
+        params = base_params.merge(amount: -100)
+        expect { item_resource.create(**params) }
+          .to raise_error(ZaiPayment::Errors::ValidationError, /amount must be a positive integer/)
+      end
+
+      it 'raises a ValidationError for zero amount' do
+        params = base_params.merge(amount: 0)
+        expect { item_resource.create(**params) }
+          .to raise_error(ZaiPayment::Errors::ValidationError, /amount must be a positive integer/)
+      end
+
+      it 'raises a ValidationError for non-integer amount' do
+        params = base_params.merge(amount: 'not_a_number')
+        expect { item_resource.create(**params) }
+          .to raise_error(ZaiPayment::Errors::ValidationError, /amount must be a positive integer/)
+      end
+    end
+
+    context 'when payment_type is invalid' do
+      it 'raises a ValidationError for invalid payment_type' do
+        params = base_params.merge(payment_type: 10)
+        expect { item_resource.create(**params) }
+          .to raise_error(ZaiPayment::Errors::ValidationError, /payment_type must be between 1 and 7/)
+      end
+    end
+  end
+
+  describe '#update' do
+    context 'when successful' do
+      before do
+        stubs.patch('/items/item_123') do |env|
+          body = JSON.parse(env.body)
+          [200, { 'Content-Type' => 'application/json' }, updated_response] if body['name'] == 'Updated Product'
+        end
+      end
+
+      let(:updated_response) do
+        {
+          'items' => {
+            'id' => 'item_123',
+            'name' => 'Updated Product',
+            'amount' => 12_000,
+            'description' => 'Updated description'
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.update('item_123', name: 'Updated Product', amount: 12_000)
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the updated item data' do
+        response = item_resource.update('item_123', name: 'Updated Product', amount: 12_000)
+        expect(response.data['name']).to eq('Updated Product')
+        expect(response.data['amount']).to eq(12_000)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect do
+          item_resource.update('', name: 'Updated Product')
+        end.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+
+    context 'when no update parameters provided' do
+      it 'raises a ValidationError' do
+        expect do
+          item_resource.update('item_123')
+        end.to raise_error(ZaiPayment::Errors::ValidationError, /At least one attribute/)
+      end
+    end
+  end
+
+  describe '#delete' do
+    context 'when successful' do
+      before do
+        stubs.delete('/items/item_123') do
+          [204, { 'Content-Type' => 'application/json' }, {}]
+        end
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.delete('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.delete('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#show_seller' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/sellers') do
+          [200, { 'Content-Type' => 'application/json' }, seller_data]
+        end
+      end
+
+      let(:seller_data) do
+        {
+          'users' => {
+            'id' => 'seller_456',
+            'email' => 'seller@example.com',
+            'first_name' => 'Jane',
+            'last_name' => 'Smith'
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show_seller('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the seller details' do
+        response = item_resource.show_seller('item_123')
+        expect(response.data['id']).to eq('seller_456')
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.show_seller('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#show_buyer' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/buyers') do
+          [200, { 'Content-Type' => 'application/json' }, buyer_data]
+        end
+      end
+
+      let(:buyer_data) do
+        {
+          'users' => {
+            'id' => 'buyer_123',
+            'email' => 'buyer@example.com',
+            'first_name' => 'John',
+            'last_name' => 'Doe'
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show_buyer('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the buyer details' do
+        response = item_resource.show_buyer('item_123')
+        expect(response.data['id']).to eq('buyer_123')
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.show_buyer('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#show_fees' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/fees') do
+          [200, { 'Content-Type' => 'application/json' }, fees_data]
+        end
+      end
+
+      let(:fees_data) do
+        {
+          'fees' => [
+            { 'id' => 'fee_1', 'amount' => 500, 'name' => 'Processing Fee' },
+            { 'id' => 'fee_2', 'amount' => 300, 'name' => 'Service Fee' }
+          ]
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show_fees('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the fees details' do
+        response = item_resource.show_fees('item_123')
+        expect(response.data.length).to eq(2)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.show_fees('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#show_wire_details' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/wire_details') do
+          [200, { 'Content-Type' => 'application/json' }, wire_data]
+        end
+      end
+
+      let(:wire_data) do
+        {
+          'items' => {
+            'wire_details' => {
+              'account_number' => '12345678',
+              'routing_number' => '987654321',
+              'bank_name' => 'Test Bank'
+            }
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show_wire_details('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the wire details' do
+        response = item_resource.show_wire_details('item_123')
+        expect(response.data['wire_details']).to be_a(Hash)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.show_wire_details('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#list_transactions' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/transactions') do |env|
+          [200, { 'Content-Type' => 'application/json' }, transactions_data] if env.params['limit'] == '10'
+        end
+      end
+
+      let(:transactions_data) do
+        {
+          'transactions' => [
+            { 'id' => 'txn_1', 'amount' => 10_000, 'state' => 'completed' },
+            { 'id' => 'txn_2', 'amount' => 5000, 'state' => 'pending' }
+          ]
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.list_transactions('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the transactions data' do
+        response = item_resource.list_transactions('item_123')
+        expect(response.data.length).to eq(2)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect do
+          item_resource.list_transactions('')
+        end.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#list_batch_transactions' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/batch_transactions') do |env|
+          [200, { 'Content-Type' => 'application/json' }, batch_data] if env.params['limit'] == '10'
+        end
+      end
+
+      let(:batch_data) do
+        {
+          'batch_transactions' => [
+            { 'id' => 'batch_1', 'amount' => 100_000, 'state' => 'completed' }
+          ]
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.list_batch_transactions('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the batch transactions data' do
+        response = item_resource.list_batch_transactions('item_123')
+        expect(response.data.length).to eq(1)
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect do
+          item_resource.list_batch_transactions('')
+        end.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe '#show_status' do
+    context 'when successful' do
+      before do
+        stubs.get('/items/item_123/status') do
+          [200, { 'Content-Type' => 'application/json' }, status_data]
+        end
+      end
+
+      let(:status_data) do
+        {
+          'items' => {
+            'id' => 'item_123',
+            'state' => 'completed',
+            'payment_state' => 'paid'
+          }
+        }
+      end
+
+      it 'returns the correct response type' do
+        response = item_resource.show_status('item_123')
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'returns the status details' do
+        response = item_resource.show_status('item_123')
+        expect(response.data['state']).to eq('completed')
+      end
+    end
+
+    context 'when item_id is blank' do
+      it 'raises a ValidationError' do
+        expect { item_resource.show_status('') }.to raise_error(ZaiPayment::Errors::ValidationError, /item_id/)
+      end
+    end
+  end
+
+  describe 'integration with ZaiPayment module' do
+    it 'is accessible through ZaiPayment.items' do
+      expect(ZaiPayment.items).to be_a(described_class)
+    end
+  end
+end
diff --git a/spec/zai_payment/resources/user_spec.rb b/spec/zai_payment/resources/user_spec.rb
index 4a21142..ac6264d 100644
--- a/spec/zai_payment/resources/user_spec.rb
+++ b/spec/zai_payment/resources/user_spec.rb
@@ -384,6 +384,43 @@
       end
     end
 
+    context 'when user_type is not present' do
+      before do
+        stubs.post('/users') do |env|
+          body = JSON.parse(env.body)
+          # API will handle default user_type (likely 'payin')
+          [201, { 'Content-Type' => 'application/json' }, created_response] if body['user_type'].nil?
+        end
+      end
+
+      let(:created_response) do
+        base_params.transform_keys(&:to_s).merge(
+          'id' => 'user-123',
+          'user_type' => 'payin' # API default
+        )
+      end
+
+      it 'allows user creation without user_type' do
+        response = user_resource.create(**base_params)
+        expect(response).to be_a(ZaiPayment::Response)
+        expect(response.success?).to be true
+      end
+
+      it 'only validates base required fields' do
+        # Should NOT require payout fields like address_line1, city, state, zip, dob
+        params = base_params # Only has: email, first_name, last_name, country
+        expect { user_resource.create(**params) }.not_to raise_error
+      end
+
+      it 'does not call validate_user_type! when user_type is nil' do
+        # This validates that the conditional check works
+        params = base_params
+        allow(user_resource).to receive(:validate_user_type!).and_call_original
+        user_resource.create(**params)
+        expect(user_resource).not_to have_received(:validate_user_type!)
+      end
+    end
+
     context 'when custom id is provided' do
       before do
         stubs.post('/users') do |env|
@@ -542,8 +579,11 @@
       end
 
       it 'accepts payout user type' do
-        params = base_params.merge(user_type: 'payout')
-        expect { user_resource.create(**params) }.not_to raise_error
+        payout_params = base_params.merge(
+          user_type: 'payout', address_line1: '123 Main St', city: 'Sydney',
+          state: 'NSW', zip: '2000', dob: '01/01/1990'
+        )
+        expect { user_resource.create(**payout_params) }.not_to raise_error
       end
 
       it 'accepts uppercase user type' do