diff --git a/src/controllers/categories.controller.js b/src/controllers/categories.controller.js
new file mode 100644
index 000000000..0b4543bdf
--- /dev/null
+++ b/src/controllers/categories.controller.js
@@ -0,0 +1,81 @@
+const categoriesService = require('../services/categories.service');
+
+const getAll = async (req, res) => {
+  const categories = await categoriesService.getAll();
+
+  res.send(categories);
+};
+
+const getOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const category = await categoriesService.getById(id);
+
+  if (!category) {
+    return res.sendStatus(404);
+  }
+
+  res.send(category);
+};
+
+const create = async (req, res) => {
+  const name = req.body.name;
+
+  if (!name || typeof name !== 'string') {
+    return res.sendStatus(400);
+  }
+
+  const category = await categoriesService.create(name);
+
+  res.status(201).json(category);
+};
+
+const deleteOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const category = await categoriesService.deleteById(id);
+
+  if (!category) {
+    return res.sendStatus(404);
+  }
+
+  res.sendStatus(204);
+};
+
+async function update(req, res) {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const { name } = req.body;
+
+  if (!name || typeof name !== 'string') {
+    return res.sendStatus(400);
+  }
+
+  const category = await categoriesService.update(id, name);
+
+  if (!category) {
+    return res.sendStatus(404);
+  }
+
+  res.send(category);
+}
+
+module.exports = {
+  getAll,
+  getOne,
+  create,
+  update,
+  deleteOne,
+};
diff --git a/src/controllers/expenses.controller.js b/src/controllers/expenses.controller.js
new file mode 100644
index 000000000..fc761e557
--- /dev/null
+++ b/src/controllers/expenses.controller.js
@@ -0,0 +1,197 @@
+const expensesService = require('../services/expenses.service');
+const usersService = require('../services/users.service');
+
+const getAll = async (req, res) => {
+  const expenses = await expensesService.getAll(req.query);
+
+  res
+    .status(200)
+    .send(expenses.map((expense) => expensesService.normalize(expense)));
+};
+
+const getOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const expense = await expensesService.getById(id);
+
+  if (!expense) {
+    return res.sendStatus(404);
+  }
+
+  res.status(200).send(expensesService.normalize(expense));
+};
+
+const create = async (req, res) => {
+  const required = ['userId', 'spentAt', 'title', 'amount'];
+
+  const hasMissingField = required.some(
+    (field) => req.body[field] === undefined,
+  );
+
+  if (hasMissingField) {
+    return res.sendStatus(400);
+  }
+
+  const { userId, spentAt, title, amount, category, note } = req.body;
+  const parsedUserId = Number(userId);
+
+  if (!Number.isInteger(parsedUserId) || parsedUserId < 1) {
+    return res.sendStatus(400);
+  }
+
+  const user = await usersService.getById(parsedUserId);
+
+  if (!user) {
+    return res.sendStatus(400);
+  }
+
+  if (
+    typeof spentAt !== 'string' ||
+    Number.isNaN(new Date(spentAt).getTime())
+  ) {
+    return res.sendStatus(400);
+  }
+
+  if (typeof title !== 'string' || title.trim() === '') {
+    return res.sendStatus(400);
+  }
+
+  const parsedAmount = Number(amount);
+
+  if (!Number.isInteger(parsedAmount) || parsedAmount < 1) {
+    return res.sendStatus(400);
+  }
+
+  if (
+    category != null &&
+    (typeof category !== 'string' || category.trim() === '')
+  ) {
+    return res.sendStatus(400);
+  }
+
+  if (note != null && typeof note !== 'string') {
+    return res.sendStatus(400);
+  }
+
+  const newExpense = await expensesService.create({
+    userId: parsedUserId,
+    spentAt: spentAt,
+    title: title.trim(),
+    amount: parsedAmount,
+    category: category?.trim() || null,
+    note: typeof note === 'string' ? note : null,
+  });
+
+  return res.status(201).send(newExpense);
+};
+
+const deleteOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const expense = await expensesService.deleteById(id);
+
+  if (!expense) {
+    return res.sendStatus(404);
+  }
+
+  res.sendStatus(204);
+};
+
+const update = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const expense = await expensesService.getById(id);
+
+  if (!expense) {
+    return res.sendStatus(404);
+  }
+
+  const { userId, spentAt, title, amount, category, note } = req.body;
+
+  const updateData = {};
+
+  if (userId !== undefined) {
+    const parsedUserId = Number(userId);
+
+    if (!Number.isInteger(parsedUserId) || parsedUserId < 1) {
+      return res.sendStatus(400);
+    }
+
+    updateData.userId = parsedUserId;
+  }
+
+  if (spentAt !== undefined) {
+    if (typeof spentAt !== 'string') {
+      return res.sendStatus(400);
+    }
+
+    const parsedDate = new Date(spentAt);
+
+    if (Number.isNaN(parsedDate.getTime())) {
+      return res.sendStatus(400);
+    }
+
+    updateData.spentAt = parsedDate;
+  }
+
+  if (title !== undefined) {
+    if (typeof title !== 'string' || title.trim() === '') {
+      return res.sendStatus(400);
+    }
+
+    updateData.title = title.trim();
+  }
+
+  if (amount !== undefined) {
+    const parsedAmount = Number(amount);
+
+    if (!Number.isInteger(parsedAmount) || parsedAmount < 1) {
+      return res.sendStatus(400);
+    }
+
+    updateData.amount = parsedAmount;
+  }
+
+  if (category !== undefined) {
+    if (
+      category !== null &&
+      (typeof category !== 'string' || category.trim() === '')
+    ) {
+      return res.sendStatus(400);
+    }
+
+    updateData.category = category?.trim() || null;
+  }
+
+  if (note !== undefined) {
+    if (note !== null && typeof note !== 'string') {
+      return res.sendStatus(400);
+    }
+
+    updateData.note = note ?? null;
+  }
+
+  const updatedExpense = await expensesService.update(id, updateData);
+
+  return res.status(200).send(expensesService.normalize(updatedExpense));
+};
+
+module.exports = {
+  getAll,
+  getOne,
+  create,
+  update,
+  deleteOne,
+};
diff --git a/src/controllers/users.controller.js b/src/controllers/users.controller.js
new file mode 100644
index 000000000..c5e9e0cce
--- /dev/null
+++ b/src/controllers/users.controller.js
@@ -0,0 +1,81 @@
+const usersService = require('../services/users.service');
+
+const getAll = async (req, res) => {
+  const users = await usersService.getAll();
+
+  res.send(users);
+};
+
+const getOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const user = await usersService.getById(id);
+
+  if (!user) {
+    return res.sendStatus(404);
+  }
+
+  res.send(user);
+};
+
+const create = async (req, res) => {
+  const name = req.body.name;
+
+  if (!name || typeof name !== 'string') {
+    return res.sendStatus(400);
+  }
+
+  const user = await usersService.create(name);
+
+  res.status(201).json(user);
+};
+
+const deleteOne = async (req, res) => {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const user = await usersService.deleteById(id);
+
+  if (!user) {
+    return res.sendStatus(404);
+  }
+
+  res.sendStatus(204);
+};
+
+async function update(req, res) {
+  const id = Number(req.params.id);
+
+  if (!Number.isInteger(id) || id < 1) {
+    return res.sendStatus(400);
+  }
+
+  const { name } = req.body;
+
+  if (!name || typeof name !== 'string') {
+    return res.sendStatus(400);
+  }
+
+  const user = await usersService.update(id, name);
+
+  if (!user) {
+    return res.sendStatus(404);
+  }
+
+  res.send(user);
+}
+
+module.exports = {
+  getAll,
+  getOne,
+  create,
+  update,
+  deleteOne,
+};
diff --git a/src/createServer.js b/src/createServer.js
index 1ea5542d6..0d5bdc172 100644
--- a/src/createServer.js
+++ b/src/createServer.js
@@ -1,8 +1,21 @@
 'use strict';
 
-const createServer = () => {
-  // your code goes here
-};
+const express = require('express');
+const { usersRouter } = require('./routes/users.route');
+const { expensesRouter } = require('./routes/expenses.route');
+const { categoriesRouter } = require('./routes/categories.route');
+
+function createServer() {
+  const app = express();
+
+  app.use(express.json());
+
+  app.use('/users', usersRouter);
+  app.use('/expenses', expensesRouter);
+  app.use('/categories', categoriesRouter);
+
+  return app;
+}
 
 module.exports = {
   createServer,
diff --git a/src/models/Category.model.js b/src/models/Category.model.js
new file mode 100644
index 000000000..3cc491012
--- /dev/null
+++ b/src/models/Category.model.js
@@ -0,0 +1,20 @@
+'use strict';
+
+const { DataTypes } = require('sequelize');
+const { sequelize } = require('../db.js');
+
+const Category = sequelize.define('Category', {
+  id: {
+    type: DataTypes.INTEGER,
+    primaryKey: true,
+    autoIncrement: true,
+  },
+  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..62b45363b 100644
--- a/src/models/Expense.model.js
+++ b/src/models/Expense.model.js
@@ -1,10 +1,39 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
-const Expense = sequelize.define(
-  // your code goes here
-);
+const Expense = sequelize.define('Expense', {
+  id: {
+    type: DataTypes.INTEGER,
+    primaryKey: true,
+    autoIncrement: true,
+  },
+  userId: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+  },
+  spentAt: {
+    type: DataTypes.STRING,
+    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..148d6b912 100644
--- a/src/models/User.model.js
+++ b/src/models/User.model.js
@@ -1,10 +1,19 @@
 'use strict';
 
+const { DataTypes } = require('sequelize');
 const { sequelize } = require('../db.js');
 
-const User = sequelize.define(
-  // your code goes here
-);
+const User = sequelize.define('User', {
+  id: {
+    type: DataTypes.INTEGER,
+    primaryKey: true,
+    autoIncrement: true,
+  },
+  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,
   },
 };
diff --git a/src/routes/categories.route.js b/src/routes/categories.route.js
new file mode 100644
index 000000000..3b2ff7353
--- /dev/null
+++ b/src/routes/categories.route.js
@@ -0,0 +1,14 @@
+const { Router } = require('express');
+const categoriesController = require('../controllers/categories.controller');
+
+const categoriesRouter = Router();
+
+categoriesRouter.get('/', categoriesController.getAll);
+categoriesRouter.get('/:id', categoriesController.getOne);
+categoriesRouter.post('/', categoriesController.create);
+categoriesRouter.patch('/:id', categoriesController.update);
+categoriesRouter.delete('/:id', categoriesController.deleteOne);
+
+module.exports = {
+  categoriesRouter,
+};
diff --git a/src/routes/expenses.route.js b/src/routes/expenses.route.js
new file mode 100644
index 000000000..c7c91f901
--- /dev/null
+++ b/src/routes/expenses.route.js
@@ -0,0 +1,14 @@
+const { Router } = require('express');
+const expensesController = require('../controllers/expenses.controller');
+
+const expensesRouter = Router();
+
+expensesRouter.get('/', expensesController.getAll);
+expensesRouter.get('/:id', expensesController.getOne);
+expensesRouter.post('/', expensesController.create);
+expensesRouter.patch('/:id', expensesController.update);
+expensesRouter.delete('/:id', expensesController.deleteOne);
+
+module.exports = {
+  expensesRouter,
+};
diff --git a/src/routes/users.route.js b/src/routes/users.route.js
new file mode 100644
index 000000000..c3e59ec15
--- /dev/null
+++ b/src/routes/users.route.js
@@ -0,0 +1,14 @@
+const { Router } = require('express');
+const usersController = require('../controllers/users.controller');
+
+const usersRouter = Router();
+
+usersRouter.get('/', usersController.getAll);
+usersRouter.get('/:id', usersController.getOne);
+usersRouter.post('/', usersController.create);
+usersRouter.delete('/:id', usersController.deleteOne);
+usersRouter.patch('/:id', usersController.update);
+
+module.exports = {
+  usersRouter,
+};
diff --git a/src/services/categories.service.js b/src/services/categories.service.js
new file mode 100644
index 000000000..1557a2336
--- /dev/null
+++ b/src/services/categories.service.js
@@ -0,0 +1,47 @@
+const { Category } = require('../models/Category.model');
+
+async function getAll() {
+  return Category.findAll();
+}
+
+async function getById(id) {
+  return Category.findByPk(id);
+}
+
+async function create(name) {
+  return Category.create({ name });
+}
+
+async function deleteById(id) {
+  return Category.destroy({ where: { id } });
+}
+
+async function update(id, name) {
+  await Category.update(
+    { name: name },
+    {
+      where: { id },
+      silent: true, // Save without updating the updatedAt timestamp
+    },
+  );
+
+  return Category.findByPk(id);
+}
+
+function normalize({ id, name, createdAt, updatedAt }) {
+  return {
+    id,
+    name,
+    createdAt,
+    updatedAt,
+  };
+}
+
+module.exports = {
+  getAll,
+  getById,
+  create,
+  deleteById,
+  update,
+  normalize,
+};
diff --git a/src/services/expenses.service.js b/src/services/expenses.service.js
new file mode 100644
index 000000000..097acba71
--- /dev/null
+++ b/src/services/expenses.service.js
@@ -0,0 +1,89 @@
+const { Expense } = require('../models/Expense.model');
+
+async function getAll(query = {}) {
+  const { userId, from, to, categories } = query;
+  const parsedUserId = userId == null ? undefined : Number(userId);
+  const expenses = await Expense.findAll();
+
+  return expenses.filter((expense) => {
+    if (parsedUserId && expense.userId !== parsedUserId) {
+      return false;
+    }
+
+    const expenseDate = new Date(expense.spentAt);
+
+    if (from && expenseDate < new Date(from)) {
+      return false;
+    }
+
+    if (to && expenseDate > new Date(to)) {
+      return false;
+    }
+
+    if (categories) {
+      const categoriesArray = Array.isArray(categories)
+        ? categories
+        : categories.split(',');
+
+      if (!categoriesArray.includes(expense.category)) {
+        return false;
+      }
+    }
+
+    return true;
+  });
+}
+
+async function getById(id) {
+  return Expense.findByPk(id);
+}
+
+async function create({ userId, spentAt, title, amount, category, note }) {
+  return Expense.create({
+    userId,
+    spentAt,
+    title,
+    amount,
+    category,
+    note,
+  });
+}
+
+async function deleteById(id) {
+  return Expense.destroy({ where: { id } });
+}
+
+async function update(id, data) {
+  const expense = await Expense.findByPk(id);
+
+  if (!expense) {
+    return null;
+  }
+
+  Object.assign(expense, data);
+
+  await expense.save();
+
+  return expense;
+}
+
+function normalize({ id, userId, spentAt, title, amount, category, note }) {
+  return {
+    id,
+    userId,
+    spentAt,
+    title,
+    amount,
+    category,
+    note,
+  };
+}
+
+module.exports = {
+  getAll,
+  getById,
+  create,
+  deleteById,
+  update,
+  normalize,
+};
diff --git a/src/services/users.service.js b/src/services/users.service.js
new file mode 100644
index 000000000..afa51e98a
--- /dev/null
+++ b/src/services/users.service.js
@@ -0,0 +1,47 @@
+const { User } = require('../models/User.model');
+
+async function getAll() {
+  return User.findAll();
+}
+
+async function getById(id) {
+  return User.findByPk(id);
+}
+
+async function create(name) {
+  return User.create({ name });
+}
+
+async function deleteById(id) {
+  return User.destroy({ where: { id } });
+}
+
+async function update(id, name) {
+  await User.update(
+    { name: name },
+    {
+      where: { id },
+      silent: true, // Save without updating the updatedAt timestamp
+    },
+  );
+
+  return User.findByPk(id);
+}
+
+function normalize({ id, name, createdAt, updatedAt }) {
+  return {
+    id,
+    name,
+    createdAt,
+    updatedAt,
+  };
+}
+
+module.exports = {
+  getAll,
+  getById,
+  create,
+  deleteById,
+  update,
+  normalize,
+};