diff --git a/src/createServer.js b/src/createServer.js
index 1ea5542d6..0db6917d0 100644
--- a/src/createServer.js
+++ b/src/createServer.js
@@ -1,9 +1,286 @@
 'use strict';
 
+const express = require('express');
+
+const { User, Expense, Category } = require('./models/models');
+
 const createServer = () => {
-  // your code goes here
-};
+  const app = express();
+
+  app.use(express.json());
+
+  app.post('/users', async (req, res) => {
+    const { name } = req.body;
+
+    if (!name) {
+      return res.status(400).send('Name is required');
+    }
+
+    try {
+      const newUser = await User.create({ name });
+
+      res.status(201).json(newUser);
+    } catch (e) {
+      res.status(400).send(e.message);
+    }
+  });
+
+  app.get('/users', async (req, res) => {
+    res.json(await User.findAll());
+  });
+
+  app.get('/users/:id', async (req, res) => {
+    const user = await User.findByPk(req.params.id);
+
+    if (!user) {
+      return res.status(404).send('User not found');
+    }
+    res.json(user);
+  });
+
+  app.patch('/users/:id', async (req, res) => {
+    const user = await User.findByPk(req.params.id);
+
+    if (!user) {
+      return res.status(404).send('Not found');
+    }
+    await user.update(req.body, { silent: true });
+    res.json(user);
+  });
+
+  app.delete('/users/:id', async (req, res) => {
+    const user = await User.findByPk(req.params.id);
+
+    if (!user) {
+      return res.status(404).send('Not found');
+    }
+    await user.destroy();
+    res.sendStatus(204);
+  });
+
+  app.post('/expenses', async (req, res) => {
+    const { title, amount, userId, category, note, spentAt } = req.body;
+
+    if (!title || !amount || !userId) {
+      return res.sendStatus(400);
+    }
+
+    try {
+      const [foundCategory] = await Category.findOrCreate({
+        where: { name: category || 'Other' },
+      });
+
+      const expense = await Expense.create({
+        title,
+        amount,
+        userId,
+        categoryId: foundCategory.id,
+        note,
+
+        spentAt: spentAt || new Date(),
+      });
+
+      const result = expense.toJSON();
+
+      delete result.categoryId;
+
+      res.status(201).json({
+        ...result,
+        category: foundCategory.name,
+      });
+    } catch (error) {
+      res.sendStatus(400);
+    }
+  });
+
+  app.get('/expenses', async (req, res) => {
+    const { userId, categories, from, to } = req.query;
+    const { Op } = require('sequelize');
+
+    const where = {};
+
+    if (userId) {
+      where.userId = userId;
+    }
+
+    if (from || to) {
+      where.spentAt = {};
+
+      if (from) {
+        where.spentAt[Op.gte] = from;
+      }
+
+      if (to) {
+        where.spentAt[Op.lte] = to;
+      }
+    }
+
+    const include = [
+      {
+        model: Category,
+        as: 'Category',
+
+        ...(categories && {
+          where: { name: categories },
+          required: true,
+        }),
+      },
+    ];
+
+    try {
+      const expenses = await Expense.findAll({
+        where,
+        include,
+      });
 
-module.exports = {
-  createServer,
+      const result = expenses.map((exp) => {
+        const data = exp.toJSON();
+
+        return {
+          id: data.id,
+          title: data.title,
+          amount: data.amount,
+          spentAt: data.spentAt,
+          note: data.note,
+          userId: data.userId,
+          category: data.Category ? data.Category.name : null,
+        };
+      });
+
+      res.json(result);
+    } catch (error) {
+      res.sendStatus(500);
+    }
+  });
+
+  app.delete('/expenses/:id', async (req, res) => {
+    const deletedCount = await Expense.destroy({
+      where: { id: req.params.id },
+    });
+
+    if (deletedCount === 0) {
+      return res.sendStatus(404);
+    }
+
+    res.sendStatus(204);
+  });
+
+  app.get('/expenses/:id', async (req, res) => {
+    const expense = await Expense.findByPk(req.params.id, {
+      include: [{ model: Category, as: 'Category' }],
+    });
+
+    if (!expense) {
+      return res.sendStatus(404);
+    }
+
+    const data = expense.toJSON();
+    const response = {
+      ...data,
+      category: data.Category ? data.Category.name : null,
+    };
+
+    delete response.Category;
+    delete response.categoryId;
+
+    res.json(response);
+  });
+
+  app.patch('/expenses/:id', async (req, res) => {
+    const expense = await Expense.findByPk(req.params.id);
+
+    if (!expense) {
+      return res.sendStatus(404);
+    }
+
+    const { category, ...otherData } = req.body;
+    const updateData = { ...otherData };
+
+    if (category) {
+      const [foundCategory] = await Category.findOrCreate({
+        where: { name: category },
+      });
+
+      updateData.categoryId = foundCategory.id;
+    }
+
+    await expense.update(updateData);
+
+    const updatedExpense = await Expense.findByPk(req.params.id, {
+      include: [{ model: Category, as: 'Category' }],
+    });
+
+    const data = updatedExpense.toJSON();
+    const response = {
+      ...data,
+      category: data.Category ? data.Category.name : null,
+    };
+
+    delete response.Category;
+    delete response.categoryId;
+
+    res.json(response);
+  });
+
+  app.get('/categories', async (req, res) => {
+    try {
+      const categories = await Category.findAll({ order: [['id', 'ASC']] });
+
+      res.json(categories);
+    } catch (e) {
+      res.status(500).json({ error: e.message });
+    }
+  });
+
+  app.post('/categories', async (req, res) => {
+    const { name } = req.body;
+
+    if (!name) {
+      return res.status(400).send('Name is required');
+    }
+
+    try {
+      const [category, created] = await Category.findOrCreate({
+        where: { name },
+      });
+
+      res.status(created ? 201 : 200).json(category);
+    } catch (e) {
+      res.status(400).json({ error: e.message });
+    }
+  });
+
+  app.patch('/categories/:id', async (req, res) => {
+    try {
+      const category = await Category.findByPk(req.params.id);
+
+      if (!category) {
+        return res.sendStatus(404);
+      }
+      await category.update(req.body);
+      res.json(category);
+    } catch (e) {
+      res.status(400).json({ error: e.message });
+    }
+  });
+
+  app.delete('/categories/:id', async (req, res) => {
+    try {
+      const category = await Category.findByPk(req.params.id);
+
+      if (!category) {
+        return res.sendStatus(404);
+      }
+      await category.destroy();
+      res.sendStatus(204);
+    } catch (e) {
+      res
+        .status(400)
+        .send('Cannot delete category: it is assigned to expenses.');
+    }
+  });
+
+  return app;
 };
+
+module.exports = { createServer };
diff --git a/src/db.js b/src/db.js
index 1ba3046cc..bd44e4875 100644
--- a/src/db.js
+++ b/src/db.js
@@ -21,12 +21,12 @@ const {
 */
 
 const sequelize = new Sequelize({
-  database: POSTGRES_DB || 'postgres',
+  database: POSTGRES_DB || 'students',
   username: POSTGRES_USER || 'postgres',
   host: POSTGRES_HOST || 'localhost',
   dialect: 'postgres',
   port: POSTGRES_PORT || 5432,
-  password: POSTGRES_PASSWORD || '123',
+  password: POSTGRES_PASSWORD || 'postgres',
 });
 
 module.exports = {
diff --git a/src/index.js b/src/index.js
index 541737327..ce0e6eb3c 100644
--- a/src/index.js
+++ b/src/index.js
@@ -4,6 +4,24 @@
 
 const { createServer } = require('./createServer');
 
-createServer().listen(5700, () => {
-  console.log('Server is running on localhost:5700');
-});
+const { sequelize } = require('./db');
+
+const app = createServer();
+const PORT = process.env.PORT || 3000;
+
+async function start() {
+  try {
+    await sequelize.authenticate();
+    console.log('Connection to PostgreSQL has been established successfully.');
+
+    await sequelize.sync({ alter: true });
+
+    app.listen(PORT, () => {
+      console.log(`Server is running on port ${PORT}`);
+    });
+  } catch (error) {
+    console.error('Unable to connect to the database:', error);
+  }
+}
+
+start();
diff --git a/src/models/Category.model.js b/src/models/Category.model.js
new file mode 100644
index 000000000..0f2c5e23d
--- /dev/null
+++ b/src/models/Category.model.js
@@ -0,0 +1,11 @@
+const { DataTypes } = require('sequelize');
+const { sequelize } = require('../db');
+
+const Category = sequelize.define('Category', {
+  name: {
+    type: DataTypes.STRING,
+    allowNull: false,
+  },
+});
+
+module.exports = { Category };
diff --git a/src/models/Expense.model.js b/src/models/Expense.model.js
index 567e1c3e7..1ca84dfbf 100644
--- a/src/models/Expense.model.js
+++ b/src/models/Expense.model.js
@@ -1,9 +1,34 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
 const Expense = sequelize.define(
-  // your code goes here
+  'Expense',
+  {
+    title: {
+      type: DataTypes.STRING,
+      allowNull: false,
+    },
+    amount: {
+      type: DataTypes.INTEGER,
+      allowNull: false,
+    },
+
+    spentAt: {
+      type: DataTypes.DATE,
+      allowNull: true,
+      defaultValue: DataTypes.NOW,
+    },
+    note: {
+      type: DataTypes.TEXT,
+      allowNull: true,
+    },
+  },
+  {
+    tableName: 'expenses',
+    timestamps: false,
+  },
 );
 
 module.exports = {
diff --git a/src/models/User.model.js b/src/models/User.model.js
index 61861c9e4..e2e2ff33b 100644
--- a/src/models/User.model.js
+++ b/src/models/User.model.js
@@ -1,9 +1,25 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
 const User = sequelize.define(
-  // your code goes here
+  'User',
+  {
+    name: {
+      type: DataTypes.STRING,
+      allowNull: false,
+    },
+  },
+  {
+    hooks: {
+      beforeBulkDestroy: (options) => {
+        if (options.truncate) {
+          options.truncate = false;
+        }
+      },
+    },
+  },
 );
 
 module.exports = {
diff --git a/src/models/models.js b/src/models/models.js
index b43b55752..ef22a6819 100644
--- a/src/models/models.js
+++ b/src/models/models.js
@@ -1,11 +1,22 @@
-'use strict';
-
 const { User } = require('./User.model');
 const { Expense } = require('./Expense.model');
+const { Category } = require('./Category.model');
+
+User.hasMany(Expense, { foreignKey: 'userId' });
+Expense.belongsTo(User, { foreignKey: 'userId' });
+
+Category.hasMany(Expense, { foreignKey: 'categoryId' });
+Expense.belongsTo(Category, { foreignKey: 'categoryId' });
+
+const models = {
+  User,
+  Expense,
+  Category,
+};
 
 module.exports = {
-  models: {
-    User,
-    Expense,
-  },
+  models,
+  User,
+  Expense,
+  Category,
 };