diff --git a/.gitignore b/.gitignore
index 7f73029..f69bb2b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .env
 .idea
-.vscode
\ No newline at end of file
+.vscode
+node_modules
\ No newline at end of file
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..8afc660
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,292 @@
+/**
+ * Canada Post API type definitions
+ */
+export declare namespace CanadaPost {
+  /** 
+   * Represents a Canada Post shipping service
+   */
+  export interface Service {
+    /** The unique code identifying the service */
+    serviceCode: string;
+    /** The human-readable name of the service */
+    serviceName: string;
+  }
+
+  export interface PriceDetails {
+    /** Base price before adjustments */
+    base: string;
+    /** Array of applicable taxes */
+    taxes: unknown[];
+    /** Array of price adjustments */
+    adjustments: unknown[];
+    /** Array of optional services and their costs */
+    options: unknown[];
+    /** Final amount due */
+    due: string;
+  }
+
+  /**
+   * Represents a price quote for a shipping service
+   */
+  export interface PriceQuote {
+    /** The unique code identifying the service */
+    serviceCode: string;
+    /** The human-readable name of the service */
+    serviceName: string;
+    /** Detailed breakdown of the price quote */
+    priceDetails: PriceDetails;
+  }
+
+  /**
+   * Links associated with a non-contract shipment
+   */
+  export interface NonContractShipmentLinks {
+    /** Map of link relations to URLs */
+    [rel: string]: string | string[];
+  }
+
+  /**
+   * Information about a non-contract shipment
+   */
+  export interface NonContractShipmentInfo {
+    /** Unique identifier for the shipment */
+    shipmentId: string;
+    /** Tracking PIN for the shipment */
+    trackingPin: string;
+    /** Associated links for various shipment operations */
+    links: NonContractShipmentLinks;
+  }
+
+  /**
+   * Response from a refund request
+   */
+  export interface RefundResponse {
+    /** Unique identifier for the service ticket */
+    serviceTicketId: string;
+    /** Date the service ticket was created */
+    serviceTicketDate: string;
+  }
+
+  /**
+   * Link information for a shipment
+   */
+  export interface ShipmentLink {
+    /** Unique identifier for the shipment */
+    shipmentId: string;
+    /** URL for the shipment resource */
+    href: string;
+    /** Media type of the resource */
+    mediaType: string;
+    /** Relationship type of the link */
+    rel: string;
+  }
+
+  /**
+   * Summary tracking information
+   */
+  export interface TrackingSummary {
+    /** Tracking PIN */
+    pin: string;
+    /** Summary of the tracking status */
+    summary: string;
+  }
+
+  export interface DeliveryOption {
+    /** The human-readable name of the delivery option */
+    description: string;
+    /** The code identifying the delivery option */
+    option: string;
+  }
+
+  /**
+   * Detailed tracking information
+   */
+  export interface TrackingDetail {
+    /** Available delivery options */
+    deliveryOptions?: DeliveryOption[];
+    /** Significant tracking events */
+    significantEvents?: Array<unknown>;
+  }
+
+  /**
+   * Represents a mailing scenario for rate calculations
+   */
+  export type MailingScenario = Record<string, unknown>;
+}
+
+/**
+ * Client for interacting with the Canada Post API
+ */
+export declare class CanadaPostClient {
+  /**
+   * Normalizes an object's keys to either camelCase or kebab-case
+   * @param obj - Object to normalize
+   * @param kebab - Whether to use kebab-case (true) or camelCase (false)
+   * @param ignoreAttrs - Whether to ignore XML attributes
+   */
+  static normalizeObject(obj: object, kebab: boolean, ignoreAttrs: boolean): object;
+
+  /**
+   * Formats a date into the required Canada Post format (YYYYMMDDHHmm)
+   * @param date - Date to format
+   */
+  static formatDate(date: Date): string;
+
+  /**
+   * Sets XML namespace on an object
+   * @param obj - Object to set namespace on
+   * @param xmlns - XML namespace to set
+   */
+  static setNamespace(obj: object, xmlns: string): object;
+
+  /**
+   * Validates the format of an API response
+   * @param result - API response to check
+   * @param path - Expected path in the response
+   * @param and - Additional condition that must be true
+   */
+  static checkResultFormat(result: object, path: string, and: boolean): void;
+
+  /**
+   * Creates a new Canada Post API client
+   * @param userId - Canada Post API user ID
+   * @param password - Canada Post API password
+   * @param customer - Customer number
+   * @param lang - Language for responses (default: en-CA)
+   * @param useTestEndpoint - Whether to use the test endpoint. Defaults to false if NODE_ENV is 'production'.
+   */
+  constructor(
+    userId: string,
+    password: string,
+    customer: string,
+    lang: string,
+    useTestEndpoint?: boolean
+  );
+
+  /** API endpoint URL */
+  endpoint: string;
+  /** Base64 encoded authentication string */
+  auth: string;
+  /** Customer number */
+  customer: string;
+  /** Response language */
+  lang: string;
+
+  /**
+   * Makes a request to the Canada Post API
+   * @param call - API endpoint to call
+   * @param params - Request parameters
+   * @param contentType - Content type for the request
+   * @param path - Optional path prefix
+   * @param method - HTTP method (default: GET)
+   */
+  _request(
+    call: string,
+    params: object | null,
+    contentType: string,
+    path?: string | null,
+    method?: string
+  ): Promise<object>;
+
+  /**
+   * Makes a raw HTTP request to the Canada Post API
+   * @param method - HTTP method
+   * @param url - Request URL
+   * @param contentType - Content type for the request
+   * @param body - Request body
+   */
+  _rawRequest(method: string, url: string, contentType: string, body: string | undefined): Promise<object>;
+
+  /**
+   * Gets available shipping services
+   * @param originPostalCode - Origin postal code
+   * @param destinationCountry - Destination country
+   * @param destinationPostalCode - Optional destination postal code
+   */
+  discoverServices(
+    originPostalCode: string,
+    destinationCountry: string,
+    destinationPostalCode?: string
+  ): Promise<CanadaPost.Service[]>;
+
+  /**
+   * Gets shipping rates for a mailing scenario
+   * @param scenario - Mailing scenario details
+   */
+  getRates(scenario: CanadaPost.MailingScenario): Promise<CanadaPost.PriceQuote[]>;
+
+  /**
+   * Creates a non-contract shipment
+   * @param shipment - Shipment details
+   */
+  createNonContractShipment(shipment: object): Promise<CanadaPost.NonContractShipmentInfo>;
+
+  /**
+   * Requests a refund for a non-contract shipment
+   * @param id - Shipment ID
+   * @param email - Email address for refund notification
+   */
+  refundNonContractShipment(
+    id: string,
+    email: string
+  ): Promise<CanadaPost.RefundResponse>;
+
+  /**
+   * Gets tracking summary for a shipment
+   * @param pin - Tracking PIN
+   * @param type - Type of tracking identifier (pin, ref, or dnc)
+   */
+  getTrackingSummary(pin: string, type?: string): Promise<CanadaPost.TrackingSummary>;
+
+  /**
+   * Gets detailed tracking information for a shipment
+   * @param pin - Tracking PIN
+   * @param type - Type of tracking identifier (pin or dnc)
+   */
+  getTrackingDetail(pin: string, type?: string): Promise<CanadaPost.TrackingDetail>;
+
+  /**
+   * Gets a list of shipments within a date range
+   * @param from - Start date
+   * @param to - Optional end date
+   */
+  getShipments(from: string | Date, to?: string | Date): Promise<CanadaPost.ShipmentLink[]>;
+
+  /**
+   * Gets information about a specific shipment
+   * @param id - Shipment ID
+   */
+  getShipment(id: string): Promise<CanadaPost.NonContractShipmentInfo>;
+
+  /**
+   * Gets detailed information about a specific shipment
+   * @param id - Shipment ID
+   */
+  getShipmentDetails(id: string): Promise<object>;
+}
+
+export declare namespace CanadaPostClient {
+  /** Production API endpoint */
+  export const ENDPOINT: string;
+  /** Development/test API endpoint */
+  export const ENDPOINT_DEV: string;
+  export { CanadaPostError };
+}
+
+/**
+ * Custom error class for Canada Post API errors
+ */
+export declare class CanadaPostError extends Error {
+  /**
+   * Creates a new Canada Post error
+   * @param message - Error message or error object(s)
+   * @param code - Error code
+   */
+  constructor(message: string | { description: string; code: string } | Array<{ description: string; code: string }>, code: string);
+  /** Error code */
+  code: string;
+  /** Original error messages from the API */
+  originalMessages: Array<{ description: string; code: string }> | [];
+}
+
+declare module "canadapost-api";
diff --git a/package.json b/package.json
index 2201cf0..3313cf2 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "1.2.0",
   "description": "A more complete Canada Post API library",
   "main": "lib/canadapost.js",
+  "types": "index.d.ts",
   "scripts": {
     "lint": "semistandard",
     "test": "npm run lint && ./node_modules/.bin/mocha --timeout 60000 ./test"
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..165454f
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,21 @@
+{
+  // Change this to match your project
+  "include": ["lib/**/*", "index.d.ts"],
+  "compilerOptions": {
+    // Tells TypeScript to read JS files, as
+    // normally they are ignored as source files
+    "allowJs": true,
+    // Generate d.ts files
+    "declaration": true,
+    // This compiler run should
+    // only output d.ts files
+    "emitDeclarationOnly": true,
+    // Types should go into this directory.
+    // Removing this would place the .d.ts files
+    // next to the .js files
+    "outDir": "dist",
+    // go to js file when using IDE functions like
+    // "Go to Definition" in VSCode
+    "declarationMap": true
+  }
+}