diff --git a/pom.xml b/pom.xml
index d2126220..3e2b25a0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1,32 +1,34 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
+<dependencies>
+    <!-- Spring Boot Starter Web -->
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
 
-    <groupId>com.houari</groupId>
-    <artifactId>Calculator</artifactId>
-    <version>1.0-SNAPSHOT</version>
+    <!-- Spring Boot Starter Data JPA -->
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-data-jpa</artifactId>
+    </dependency>
 
-    <properties>
-        <maven.compiler.source>11</maven.compiler.source>
-        <maven.compiler.target>11</maven.compiler.target>
-        <jackson-dataformat-yaml.version>2.14.2</jackson-dataformat-yaml.version>
-        <junit-jupiter-params.version>5.9.2</junit-jupiter-params.version>
-    </properties>
+    <!-- H2 Database for Testing -->
+    <dependency>
+        <groupId>com.h2database</groupId>
+        <artifactId>h2</artifactId>
+        <scope>runtime</scope>
+    </dependency>
 
-    <dependencies>
-        <dependency>
-            <groupId>com.fasterxml.jackson.dataformat</groupId>
-            <artifactId>jackson-dataformat-yaml</artifactId>
-            <version>${jackson-dataformat-yaml.version}</version>
-        </dependency>
+    <!-- Lombok for Cleaner Code -->
+    <dependency>
+        <groupId>org.projectlombok</groupId>
+        <artifactId>lombok</artifactId>
+        <scope>provided</scope>
+    </dependency>
 
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter-params</artifactId>
-            <version>${junit-jupiter-params.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-</project>
\ No newline at end of file
+    <!-- Spring Boot Test for TDD -->
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-test</artifactId>
+        <scope>test</scope>
+    </dependency>
+</dependencies>
diff --git a/src/main/java/com/houarizegai/calculator/controller/CalculatorController.java b/src/main/java/com/houarizegai/calculator/controller/CalculatorController.java
new file mode 100644
index 00000000..dbc3bee7
--- /dev/null
+++ b/src/main/java/com/houarizegai/calculator/controller/CalculatorController.java
@@ -0,0 +1,35 @@
+package com.example.calculator.controller;
+
+import com.example.calculator.service.CalculatorService;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/calculator")
+public class CalculatorController {
+
+    private final CalculatorService calculatorService;
+
+    public CalculatorController(CalculatorService calculatorService) {
+        this.calculatorService = calculatorService;
+    }
+
+    @GetMapping("/add")
+    public int add(@RequestParam int a, @RequestParam int b) {
+        return calculatorService.add(a, b);
+    }
+
+    @GetMapping("/subtract")
+    public int subtract(@RequestParam int a, @RequestParam int b) {
+        return calculatorService.subtract(a, b);
+    }
+
+    @GetMapping("/multiply")
+    public int multiply(@RequestParam int a, @RequestParam int b) {
+        return calculatorService.multiply(a, b);
+    }
+
+    @GetMapping("/divide")
+    public int divide(@RequestParam int a, @RequestParam int b) {
+        return calculatorService.divide(a, b);
+    }
+}
diff --git a/src/main/java/com/houarizegai/calculator/tdd/service/userService.java b/src/main/java/com/houarizegai/calculator/tdd/service/userService.java
new file mode 100644
index 00000000..f7164579
--- /dev/null
+++ b/src/main/java/com/houarizegai/calculator/tdd/service/userService.java
@@ -0,0 +1,25 @@
+package com.example.tdd.service;
+
+import com.example.tdd.model.User;
+import com.example.tdd.repository.UserRepository;
+import org.springframework.stereotype.Service;
+import java.util.Optional;
+
+@Service
+public class UserService {
+
+    private final UserRepository userRepository;
+
+    public UserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+    public User createUser(User user) {
+        return userRepository.save(user);
+    }
+
+    public User getUserById(Long id) {
+        Optional<User> user = userRepository.findById(id);
+        return user.orElseThrow(() -> new RuntimeException("User not found"));
+    }
+}
diff --git a/src/main/java/com/houarizegai/calculator/tdd/service/userServiceTest.java b/src/main/java/com/houarizegai/calculator/tdd/service/userServiceTest.java
new file mode 100644
index 00000000..4de5d124
--- /dev/null
+++ b/src/main/java/com/houarizegai/calculator/tdd/service/userServiceTest.java
@@ -0,0 +1,36 @@
+package com.example.tdd.service;
+
+import com.example.tdd.model.User;
+import com.example.tdd.repository.UserRepository;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import static org.junit.jupiter.api.Assertions.*;
+import java.util.Optional;
+
+class UserServiceTest {
+    
+    private final UserRepository userRepository = Mockito.mock(UserRepository.class);
+    private final UserService userService = new UserService(userRepository);
+
+    @Test
+    void testCreateUser() {
+        User user = new User(1L, "John Doe", "john@example.com");
+
+        Mockito.when(userRepository.save(user)).thenReturn(user);
+
+        User createdUser = userService.createUser(user);
+        assertNotNull(createdUser);
+        assertEquals("John Doe", createdUser.getName());
+    }
+
+    @Test
+    void testFindUserById() {
+        User user = new User(1L, "John Doe", "john@example.com");
+
+        Mockito.when(userRepository.findById(1L)).thenReturn(Optional.of(user));
+
+        User foundUser = userService.getUserById(1L);
+        assertNotNull(foundUser);
+        assertEquals("John Doe", foundUser.getName());
+    }
+}
diff --git a/src/main/java/com/houarizegai/calculator/tdd/userModal.java b/src/main/java/com/houarizegai/calculator/tdd/userModal.java
new file mode 100644
index 00000000..2a2cdeef
--- /dev/null
+++ b/src/main/java/com/houarizegai/calculator/tdd/userModal.java
@@ -0,0 +1,20 @@
+package com.example.tdd.model;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class User {
+    
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+    
+    private String name;
+    private String email;
+}
diff --git a/src/main/java/com/houarizegai/calculator/tdd/userRepository.java b/src/main/java/com/houarizegai/calculator/tdd/userRepository.java
new file mode 100644
index 00000000..30d56d91
--- /dev/null
+++ b/src/main/java/com/houarizegai/calculator/tdd/userRepository.java
@@ -0,0 +1,7 @@
+package com.example.tdd.repository;
+
+import com.example.tdd.model.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UserRepository extends JpaRepository<User, Long> {
+}
diff --git a/src/test/java/com/houarizegai/calculator/Calculator.code-workspace b/src/test/java/com/houarizegai/calculator/Calculator.code-workspace
new file mode 100644
index 00000000..90d9b35a
--- /dev/null
+++ b/src/test/java/com/houarizegai/calculator/Calculator.code-workspace
@@ -0,0 +1,8 @@
+{
+	"folders": [
+		{
+			"path": "../../../../../.."
+		}
+	],
+	"settings": {}
+}
\ No newline at end of file
diff --git a/src/test/java/com/houarizegai/calculator/CalculatorService.java b/src/test/java/com/houarizegai/calculator/CalculatorService.java
new file mode 100644
index 00000000..784631c2
--- /dev/null
+++ b/src/test/java/com/houarizegai/calculator/CalculatorService.java
@@ -0,0 +1,26 @@
+package com.example.calculator.service;
+
+import org.springframework.stereotype.Service;
+
+@Service
+public class CalculatorService {
+
+    public int add(int a, int b) {
+        return a + b;
+    }
+
+    public int subtract(int a, int b) {
+        return a - b;
+    }
+
+    public int multiply(int a, int b) {
+        return a * b;
+    }
+
+    public int divide(int a, int b) {
+        if (b == 0) {
+            throw new ArithmeticException("Cannot divide by zero");
+        }
+        return a / b;
+    }
+}
diff --git a/src/test/java/com/houarizegai/calculator/CalculatorUITest.java b/src/test/java/com/houarizegai/calculator/CalculatorUITest.java
index 1c617ee5..d926522c 100644
--- a/src/test/java/com/houarizegai/calculator/CalculatorUITest.java
+++ b/src/test/java/com/houarizegai/calculator/CalculatorUITest.java
@@ -1,24 +1,41 @@
-package com.houarizegai.calculator;
+package com.example.calculator.service;
 
-import com.houarizegai.calculator.ui.CalculatorUI;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.CsvSource;
+import static org.junit.jupiter.api.Assertions.*;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
-class CalculatorUITest {
+class CalculatorServiceTest {
 
-    private CalculatorUI calculatorUI;
+    private CalculatorService calculatorService;
 
     @BeforeEach
     void setUp() {
-        calculatorUI = new CalculatorUI();
+        calculatorService = new CalculatorService();
+    }
+
+    @Test
+    void testAddition() {
+        assertEquals(10, calculatorService.add(5, 5));
+    }
+
+    @Test
+    void testSubtraction() {
+        assertEquals(3, calculatorService.subtract(8, 5));
+    }
+
+    @Test
+    void testMultiplication() {
+        assertEquals(20, calculatorService.multiply(4, 5));
+    }
+
+    @Test
+    void testDivision() {
+        assertEquals(2, calculatorService.divide(10, 5));
     }
 
-    @ParameterizedTest
-    @CsvSource({"3,5,+,8", "2,8,-,-6", "44.5,10,*,445", "320,5,/,64", "3,5,%,3", "5,3,^,125"})
-    void testCalculation(double firstNumber, double secondNumber, char operator, double expectedResult) {
-        assertEquals(expectedResult, calculatorUI.calculate(firstNumber, secondNumber, operator));
+    @Test
+    void testDivisionByZero() {
+        assertThrows(ArithmeticException.class, () -> calculatorService.divide(10, 0));
     }
 }