diff --git a/src/createServer.js b/src/createServer.js
index 1ea5542d6..ad3a8ce16 100644
--- a/src/createServer.js
+++ b/src/createServer.js
@@ -1,7 +1,467 @@
 'use strict';
 
+const express = require('express');
+const { Op } = require('sequelize');
+const { User } = require('./models/User.model');
+const { Expense } = require('./models/Expense.model');
+const { Category } = require('./models/Category.model');
+
+const prepareExpense = (expense) => {
+  const { createdAt, updatedAt, ...preparedExpense } = expense.toJSON();
+
+  return preparedExpense;
+};
+
 const createServer = () => {
-  // your code goes here
+  const app = express();
+
+  app.use(express.json());
+
+  app.get('/users', async (req, res) => {
+    const result = await User.findAll();
+
+    res.send(result);
+  });
+
+  app.post('/users', async (req, res) => {
+    const { name } = req.body;
+
+    if (typeof name !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const user = await User.create({ name });
+
+    res.status(201).json(user);
+  });
+
+  app.get('/users/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const user = await User.findByPk(id);
+
+    if (!user) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.json(user);
+  });
+
+  app.patch('/users/:id', async (req, res) => {
+    const id = Number(req.params.id);
+    const { name } = req.body;
+
+    if (Number.isNaN(id)) {
+      return res.sendStatus(400);
+    }
+
+    if (typeof name !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const user = await User.findByPk(id);
+
+    if (!user) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    await user.update({ name }, { silent: true });
+
+    res.json(user);
+  });
+
+  app.delete('/users/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const deletedCount = await User.destroy({
+      where: { id },
+    });
+
+    if (deletedCount === 0) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.sendStatus(204);
+  });
+
+  app.get('/expenses', async (req, res) => {
+    const { userId, categories, from, to } = req.query;
+
+    const where = {};
+
+    if (userId !== undefined) {
+      const parsedUserId = Number(userId);
+
+      if (Number.isNaN(parsedUserId)) {
+        res.sendStatus(400);
+
+        return;
+      }
+
+      where.userId = parsedUserId;
+    }
+
+    if (categories !== undefined) {
+      const categoriesArray = Array.isArray(categories)
+        ? categories
+        : [categories];
+
+      where.category = {
+        [Op.in]: categoriesArray,
+      };
+    }
+
+    if (from !== undefined || to !== undefined) {
+      where.spentAt = {};
+
+      if (from !== undefined) {
+        const fromDate = new Date(from);
+
+        if (isNaN(fromDate.getTime())) {
+          res.sendStatus(400);
+
+          return;
+        }
+
+        where.spentAt[Op.gte] = fromDate;
+      }
+
+      if (to !== undefined) {
+        const toDate = new Date(to);
+
+        if (isNaN(toDate.getTime())) {
+          res.sendStatus(400);
+
+          return;
+        }
+
+        where.spentAt[Op.lte] = toDate;
+      }
+    }
+
+    const expenses = await Expense.findAll({ where });
+
+    res.json(expenses.map(prepareExpense));
+  });
+
+  app.post('/expenses', async (req, res) => {
+    const { userId, spentAt, title, amount, category, note } = req.body;
+
+    if (
+      typeof userId !== 'number' ||
+      typeof spentAt !== 'string' ||
+      typeof title !== 'string' ||
+      typeof amount !== 'number'
+    ) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (category !== undefined && typeof category !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const user = await User.findByPk(userId);
+
+    if (!user) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const expense = await Expense.create({
+      userId,
+      spentAt,
+      title,
+      amount,
+      ...(category !== undefined ? { category } : {}),
+      ...(note !== undefined ? { note } : {}),
+    });
+
+    return res.status(201).json(prepareExpense(expense));
+  });
+
+  app.get('/expenses/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const expense = await Expense.findByPk(id);
+
+    if (!expense) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.json(prepareExpense(expense));
+  });
+
+  app.patch('/expenses/:id', async (req, res) => {
+    const id = Number(req.params.id);
+    const { spentAt, title, amount, category, note } = req.body;
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const expense = await Expense.findByPk(id);
+
+    if (!expense) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    const hasNoFields =
+      spentAt === undefined &&
+      title === undefined &&
+      amount === undefined &&
+      category === undefined &&
+      note === undefined;
+
+    if (hasNoFields) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (spentAt !== undefined) {
+      if (typeof spentAt !== 'string') {
+        res.sendStatus(400);
+
+        return;
+      }
+
+      const spentAtDate = new Date(spentAt);
+
+      if (Number.isNaN(spentAtDate.getTime())) {
+        res.sendStatus(400);
+
+        return;
+      }
+    }
+
+    if (title !== undefined && typeof title !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (amount !== undefined && typeof amount !== 'number') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (category !== undefined && typeof category !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (note !== undefined && note !== null && typeof note !== 'string') {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const updatedFields = {};
+
+    if (spentAt !== undefined) {
+      updatedFields.spentAt = spentAt;
+    }
+
+    if (title !== undefined) {
+      updatedFields.title = title;
+    }
+
+    if (amount !== undefined) {
+      updatedFields.amount = amount;
+    }
+
+    if (category !== undefined) {
+      updatedFields.category = category;
+    }
+
+    if (note !== undefined) {
+      updatedFields.note = note;
+    }
+
+    await expense.update(updatedFields);
+
+    res.json(prepareExpense(expense));
+  });
+
+  app.delete('/expenses/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const deletedCount = await Expense.destroy({
+      where: { id },
+    });
+
+    if (deletedCount === 0) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.sendStatus(204);
+  });
+
+  app.get('/categories', async (req, res) => {
+    const categories = await Category.findAll();
+
+    res.json(categories);
+  });
+
+  app.post('/categories', async (req, res) => {
+    const { name } = req.body;
+
+    if (typeof name !== 'string' || !name.trim()) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const existingCategory = await Category.findOne({
+      where: { name: name.trim() },
+    });
+
+    if (existingCategory) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const category = await Category.create({
+      name: name.trim(),
+    });
+
+    res.status(201).json(category);
+  });
+
+  app.get('/categories/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const category = await Category.findByPk(id);
+
+    if (!category) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.json(category);
+  });
+
+  app.patch('/categories/:id', async (req, res) => {
+    const id = Number(req.params.id);
+    const { name } = req.body;
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    if (typeof name !== 'string' || !name.trim()) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const category = await Category.findByPk(id);
+
+    if (!category) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    const existingCategory = await Category.findOne({
+      where: { name: name.trim() },
+    });
+
+    if (existingCategory && existingCategory.id !== id) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    await category.update({
+      name: name.trim(),
+    });
+
+    res.json(category);
+  });
+
+  app.delete('/categories/:id', async (req, res) => {
+    const id = Number(req.params.id);
+
+    if (Number.isNaN(id)) {
+      res.sendStatus(400);
+
+      return;
+    }
+
+    const deletedCount = await Category.destroy({
+      where: { id },
+    });
+
+    if (deletedCount === 0) {
+      res.sendStatus(404);
+
+      return;
+    }
+
+    res.sendStatus(204);
+  });
+
+  return app;
 };
 
 module.exports = {
diff --git a/src/db.js b/src/db.js
index 1ba3046cc..8226c6fc0 100644
--- a/src/db.js
+++ b/src/db.js
@@ -26,7 +26,7 @@ const sequelize = new Sequelize({
   host: POSTGRES_HOST || 'localhost',
   dialect: 'postgres',
   port: POSTGRES_PORT || 5432,
-  password: POSTGRES_PASSWORD || '123',
+  password: POSTGRES_PASSWORD,
 });
 
 module.exports = {
diff --git a/src/models/Category.model.js b/src/models/Category.model.js
new file mode 100644
index 000000000..53ebcb9af
--- /dev/null
+++ b/src/models/Category.model.js
@@ -0,0 +1,23 @@
+'use strict';
+
+const { DataTypes } = require('sequelize');
+const { sequelize } = require('../db.js');
+
+const Category = sequelize.define(
+  'Category',
+  {
+    name: {
+      type: DataTypes.STRING,
+      allowNull: false,
+      unique: true,
+    },
+  },
+  {
+    tableName: 'categories',
+    timestamps: false,
+  },
+);
+
+module.exports = {
+  Category,
+};
diff --git a/src/models/Expense.model.js b/src/models/Expense.model.js
index 567e1c3e7..0f83fbd10 100644
--- a/src/models/Expense.model.js
+++ b/src/models/Expense.model.js
@@ -1,10 +1,34 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
-const Expense = sequelize.define(
-  // your code goes here
-);
+const Expense = sequelize.define('Expense', {
+  userId: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+  },
+  spentAt: {
+    type: DataTypes.DATE,
+    allowNull: false,
+  },
+  title: {
+    type: DataTypes.STRING,
+    allowNull: false,
+  },
+  amount: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+  },
+  category: {
+    type: DataTypes.STRING,
+    allowNull: true,
+  },
+  note: {
+    type: DataTypes.STRING,
+    allowNull: true,
+  },
+});
 
 module.exports = {
   Expense,
diff --git a/src/models/User.model.js b/src/models/User.model.js
index 61861c9e4..d159c5182 100644
--- a/src/models/User.model.js
+++ b/src/models/User.model.js
@@ -1,10 +1,14 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
-const User = sequelize.define(
-  // your code goes here
-);
+const User = sequelize.define('User', {
+  name: {
+    type: DataTypes.STRING,
+    allowNull: false,
+  },
+});
 
 module.exports = {
   User,
diff --git a/src/models/models.js b/src/models/models.js
index b43b55752..544e0a26a 100644
--- a/src/models/models.js
+++ b/src/models/models.js
@@ -2,10 +2,12 @@
 
 const { User } = require('./User.model');
 const { Expense } = require('./Expense.model');
+const { Category } = require('./Category.model');
 
 module.exports = {
   models: {
     User,
     Expense,
+    Category,
   },
 };