diff --git a/backend/.env.example b/backend/.env.example
new file mode 100644
index 0000000..c743b02
--- /dev/null
+++ b/backend/.env.example
@@ -0,0 +1,13 @@
+# Server
+PORT=3000
+NODE_ENV=development
+
+# Database
+DATABASE_URL=postgresql://user:password@localhost:5432/optihack
+
+# JWT
+JWT_SEED=your_super_secret_jwt_seed_here_change_in_production
+JWT_EXPIRES_IN=7d
+
+# Bcrypt
+BCRYPT_ROUNDS=10
diff --git a/backend/prisma.config.ts b/backend/prisma.config.ts
index 3c45216..60d6fe9 100644
--- a/backend/prisma.config.ts
+++ b/backend/prisma.config.ts
@@ -10,6 +10,6 @@ export default defineConfig({
     path: "prisma/migrations",
   },
   datasource: {
-      url: env("POSTGRES_URL"),
+    url: env("DATABASE_URL"),
   },
 });
diff --git a/backend/src/app.ts b/backend/src/app.ts
index 071cf34..40fd2ec 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -1,15 +1,34 @@
+/**
+ * app.ts
+ * Punto de entrada de la aplicación.
+ * - Inicia el servidor
+ * - Conecta a la base de datos
+ * - Maneja errores globales
+ */
+
+import "dotenv/config";
 import { env } from "./config/env.js";
 import { AppRoutes } from "./presentation/routes.js";
 import { Server } from "./presentation/server.js";
-
+import { prisma } from "./data/postgres/index.js";
 
 async function main() {
-    const server = new Server( {
-        port : env.PORT,
-        routes : AppRoutes.routes,
-});
-    await server.start();
+  try {
+    // Verificar conexión a la base de datos
+    await prisma.$connect();
+    console.log("✓ Database connected");
 
+    // Crear y iniciar el servidor
+    const server = new Server({
+      port: env.PORT,
+      routes: AppRoutes.routes,
+    });
+
+    await server.start();
+  } catch (error) {
+    console.error("✗ Error starting application:", error);
+    process.exit(1);
+  }
 }
 
 main();
\ No newline at end of file
diff --git a/backend/src/config/bcrypt.ts b/backend/src/config/bcrypt.ts
new file mode 100644
index 0000000..bcc6e62
--- /dev/null
+++ b/backend/src/config/bcrypt.ts
@@ -0,0 +1,18 @@
+/**
+ * bcrypt.ts
+ * BcryptAdapter: hashea y compara contraseñas.
+ * Encapsula toda la lógica de bcrypt en un lugar.
+ */
+
+import bcrypt from "bcryptjs";
+import { env } from "./env.js";
+
+export class BcryptAdapter {
+  static async hash(password: string): Promise<string> {
+    return bcrypt.hash(password, env.BCRYPT_ROUNDS);
+  }
+
+  static async compare(password: string, hash: string): Promise<boolean> {
+    return bcrypt.compare(password, hash);
+  }
+}
diff --git a/backend/src/config/env.ts b/backend/src/config/env.ts
index a631686..b599db4 100644
--- a/backend/src/config/env.ts
+++ b/backend/src/config/env.ts
@@ -1,9 +1,38 @@
-import 'dotenv/config';
-import envVar from 'env-var';
+/**
+ * env.ts
+ * Lee y valida las variables de entorno.
+ * Centraliza toda la configuración que viene del .env
+ */
+
+const getEnvVar = (key: string, defaultValue?: string): string => {
+  const value = process.env[key];
+  if (!value && defaultValue === undefined) {
+    throw new Error(`Missing environment variable: ${key}`);
+  }
+  return (value as string) || (defaultValue as string);
+};
+
+const requiredEnvVar = (key: string): string => {
+  const value = process.env[key];
+  if (!value) {
+    throw new Error(`Missing required environment variable: ${key}`);
+  }
+  return value;
+};
 
 export const env = {
-    PORT: envVar.get('PORT').required().asPortNumber(),
-    PUBLIC_PATH: envVar.get('PUBLIC_PATH').default('public').asString(),
-    POSTGRES_URL: envVar.get('POSTGRES_URL').required().asString()
-}
+  // Server
+  PORT: Number(getEnvVar("PORT", "3000")),
+  NODE_ENV: getEnvVar("NODE_ENV", "development"),
+
+  // Database
+  DATABASE_URL: requiredEnvVar("DATABASE_URL"),
+
+  // JWT
+  JWT_SEED: requiredEnvVar("JWT_SEED"),
+  JWT_EXPIRES_IN: getEnvVar("JWT_EXPIRES_IN", "7d"),
+
+  // Bcrypt
+  BCRYPT_ROUNDS: Number(getEnvVar("BCRYPT_ROUNDS", "10")),
+} as const;
 
diff --git a/backend/src/config/jwt.ts b/backend/src/config/jwt.ts
index 1b1ff37..73ec18e 100644
--- a/backend/src/config/jwt.ts
+++ b/backend/src/config/jwt.ts
@@ -1,18 +1,23 @@
-import jwt, { SignOptions } from 'jsonwebtoken';
+import jwt, { SignOptions } from "jsonwebtoken";
+import { env } from "./env.js";
 
-const JWT_SECRET = process.env.JWT_SECRET ?? 'dev_secret';
-const JWT_EXPIRES_IN = process.env.JWT_EXPIRES_IN ?? '2h';
+export interface JwtPayload {
+  id: number;
+  email: string;
+}
 
 export class JwtAdapter {
-  static generateToken(payload: object): string {
-    return jwt.sign(payload, JWT_SECRET, {
-      expiresIn: JWT_EXPIRES_IN,
-    } as SignOptions);
+  static generate(payload: JwtPayload): string {
+    const options: SignOptions = {
+      expiresIn: env.JWT_EXPIRES_IN as NonNullable<SignOptions["expiresIn"]>,
+    };
+
+    return jwt.sign(payload, env.JWT_SEED, options);
   }
 
-  static validateToken<T>(token: string): T | null {
+  static validate(token: string): JwtPayload | null {
     try {
-      return jwt.verify(token, JWT_SECRET) as T;
+      return jwt.verify(token, env.JWT_SEED) as JwtPayload;
     } catch {
       return null;
     }
diff --git a/backend/src/data/postgres/index.ts b/backend/src/data/postgres/index.ts
index 5d90ca3..a14c73d 100644
--- a/backend/src/data/postgres/index.ts
+++ b/backend/src/data/postgres/index.ts
@@ -1,9 +1,14 @@
 
-import { env } from "../../config/env.js";
-import { PrismaPg } from "@prisma/adapter-pg";
+
+import "dotenv/config";
 import { PrismaClient } from "../../generated/prisma/client.js";
- 
-const connectionString = `${env.POSTGRES_URL}`;
-const adapter = new PrismaPg({ connectionString });
- 
-export const prisma = new PrismaClient({ adapter });
\ No newline at end of file
+import { PrismaPg } from "@prisma/adapter-pg";
+
+const adapter = new PrismaPg({
+  connectionString: process.env.DATABASE_URL!,
+});
+
+export const prisma = new PrismaClient({
+  adapter,
+  errorFormat: "pretty",
+});
\ No newline at end of file
diff --git a/backend/src/data/repositories/auth.repository.impl.ts b/backend/src/data/repositories/auth.repository.impl.ts
new file mode 100644
index 0000000..3fec4d7
--- /dev/null
+++ b/backend/src/data/repositories/auth.repository.impl.ts
@@ -0,0 +1,45 @@
+/**
+ * auth.repository.impl.ts
+ * AuthRepositoryImpl: implementación real del AuthRepository.
+ * Aquí es donde hablamos con la base de datos usando Prisma.
+ */
+
+import { AuthRepository } from "../../domain/repositories/auth.repository.js";
+import { prisma } from "../postgres/index.js";
+
+export class AuthRepositoryImpl implements AuthRepository {
+  async findByEmail(email: string) {
+    return prisma.user.findUnique({
+      where: { email },
+      select: {
+        id: true,
+        email: true,
+        password: true,
+        name: true,
+      },
+    });
+  }
+
+  async create(data: { name: string; email: string; password: string }) {
+    return prisma.user.create({
+      data,
+      select: {
+        id: true,
+        email: true,
+        name: true,
+      },
+    });
+  }
+
+  async findById(id: number) {
+    return prisma.user.findUnique({
+      where: { id },
+      select: {
+        id: true,
+        email: true,
+        name: true,
+        role: true,
+      },
+    });
+  }
+}
\ No newline at end of file
diff --git a/backend/src/domain/dtos/auth/login-user.dto.ts b/backend/src/domain/dtos/auth/login-user.dto.ts
index aec887b..9965c85 100644
--- a/backend/src/domain/dtos/auth/login-user.dto.ts
+++ b/backend/src/domain/dtos/auth/login-user.dto.ts
@@ -1,15 +1,38 @@
-export class LoginUserDto {
-  private constructor(
-    public readonly email: string,
-    public readonly password: string,
-  ) {}
+/**
+ * login-user.dto.ts
+ * DTO para iniciar sesión.
+ * Define qué datos esperamos al hacer login.
+ */
 
-  static create(props: { [key: string]: any }): [string | undefined, LoginUserDto?] {
-    const { email, password } = props;
+export interface LoginUserDto {
+  email: string;
+  password: string;
+}
 
-    if (!email) return ['email is required'];
-    if (!password) return ['password is required'];
+export class LoginUserDtoValidator {
+  static validate(data: unknown): LoginUserDto {
+    if (typeof data !== "object" || data === null) {
+      throw new Error("Invalid data");
+    }
 
-    return [undefined, new LoginUserDto(email, password)];
+    const obj = data as Record<string, unknown>;
+
+    if (typeof obj.email !== "string" || !this.isValidEmail(obj.email)) {
+      throw new Error("Email is required and must be valid");
+    }
+
+    if (typeof obj.password !== "string" || obj.password.length === 0) {
+      throw new Error("Password is required");
+    }
+
+    return {
+      email: obj.email.trim().toLowerCase(),
+      password: obj.password,
+    };
+  }
+
+  private static isValidEmail(email: string): boolean {
+    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+    return emailRegex.test(email);
   }
 }
\ No newline at end of file
diff --git a/backend/src/domain/dtos/auth/register-user.dto.ts b/backend/src/domain/dtos/auth/register-user.dto.ts
index 59f623a..3266f8b 100644
--- a/backend/src/domain/dtos/auth/register-user.dto.ts
+++ b/backend/src/domain/dtos/auth/register-user.dto.ts
@@ -1,21 +1,44 @@
-export class RegisterUserDto {
-  private constructor(
-    public readonly name: string,
-    public readonly email: string,
-    public readonly password: string,
-  ) {}
+/**
+ * register-user.dto.ts
+ * DTO para registrar un usuario.
+ * Define qué datos esperamos al registrar.
+ */
 
-  static create(props: { [key: string]: any }): [string | undefined, RegisterUserDto?] {
-    const { name, email, password } = props;
+export interface RegisterUserDto {
+  name: string;
+  email: string;
+  password: string;
+}
 
-    if (!name) return ['name is required'];
-    if (!email) return ['email is required'];
-    if (!password) return ['password is required'];
-
-    if (password.length < 6) {
-      return ['password must be at least 6 characters'];
+export class RegisterUserDtoValidator {
+  static validate(data: unknown): RegisterUserDto {
+    if (typeof data !== "object" || data === null) {
+      throw new Error("Invalid data");
     }
 
-    return [undefined, new RegisterUserDto(name, email, password)];
+    const obj = data as Record<string, unknown>;
+
+    if (typeof obj.name !== "string" || obj.name.trim().length === 0) {
+      throw new Error("Name is required and must be a non-empty string");
+    }
+
+    if (typeof obj.email !== "string" || !this.isValidEmail(obj.email)) {
+      throw new Error("Email is required and must be valid");
+    }
+
+    if (typeof obj.password !== "string" || obj.password.length < 6) {
+      throw new Error("Password is required and must be at least 6 characters");
+    }
+
+    return {
+      name: obj.name.trim(),
+      email: obj.email.trim().toLowerCase(),
+      password: obj.password,
+    };
+  }
+
+  private static isValidEmail(email: string): boolean {
+    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+    return emailRegex.test(email);
   }
 }
\ No newline at end of file
diff --git a/backend/src/domain/errors/custom.error.ts b/backend/src/domain/errors/custom.error.ts
new file mode 100644
index 0000000..4315215
--- /dev/null
+++ b/backend/src/domain/errors/custom.error.ts
@@ -0,0 +1,35 @@
+/**
+ * custom.error.ts
+ * CustomError: clase base para errores personalizados.
+ * Facilita el manejo de errores en toda la aplicación.
+ */
+
+export class CustomError extends Error {
+  constructor(
+    public message: string,
+    public statusCode: number,
+  ) {
+    super(message);
+    this.name = "CustomError";
+  }
+
+  static badRequest(message: string): CustomError {
+    return new CustomError(message, 400);
+  }
+
+  static unauthorized(message: string = "Unauthorized"): CustomError {
+    return new CustomError(message, 401);
+  }
+
+  static notFound(message: string): CustomError {
+    return new CustomError(message, 404);
+  }
+
+  static conflict(message: string): CustomError {
+    return new CustomError(message, 409);
+  }
+
+  static internalServer(message: string = "Internal Server Error"): CustomError {
+    return new CustomError(message, 500);
+  }
+}
diff --git a/backend/src/domain/repositories/auth.repository.ts b/backend/src/domain/repositories/auth.repository.ts
new file mode 100644
index 0000000..b89b37d
--- /dev/null
+++ b/backend/src/domain/repositories/auth.repository.ts
@@ -0,0 +1,11 @@
+/**
+ * auth.repository.ts
+ * AuthRepository (interfaz): define qué métodos debe tener el repositorio de auth.
+ * El use-case usa esta interfaz sin saber cómo se implementa.
+ */
+
+export interface AuthRepository {
+  findByEmail(email: string): Promise<{ id: number; email: string; password: string; name: string } | null>;
+  create(data: { name: string; email: string; password: string }): Promise<{ id: number; email: string; name: string }>;
+  findById(id: number): Promise<{ id: number; email: string; name: string; role: string } | null>;
+}
\ No newline at end of file
diff --git a/backend/src/domain/use-cases/auth/get-me.use-case.ts b/backend/src/domain/use-cases/auth/get-me.use-case.ts
new file mode 100644
index 0000000..dbc73d0
--- /dev/null
+++ b/backend/src/domain/use-cases/auth/get-me.use-case.ts
@@ -0,0 +1,30 @@
+/**
+ * get-me.use-case.ts
+ * GetMeUseCase: obtiene los datos del usuario autenticado.
+ * - Busca el usuario por ID (que viene del JWT)
+ * - Retorna los datos del usuario
+ */
+
+import { AuthRepository } from "../../repositories/auth.repository.js";
+import { CustomError } from "../../errors/custom.error.js";
+
+export interface GetMeResponse {
+  id: number;
+  email: string;
+  name: string;
+  role: string;
+}
+
+export class GetMeUseCase {
+  constructor(private repository: AuthRepository) {}
+
+  async execute(userId: number): Promise<GetMeResponse> {
+    const user = await this.repository.findById(userId);
+
+    if (!user) {
+      throw CustomError.notFound("User not found");
+    }
+
+    return user as GetMeResponse;
+  }
+}
\ No newline at end of file
diff --git a/backend/src/domain/use-cases/auth/login-user.use-case.ts b/backend/src/domain/use-cases/auth/login-user.use-case.ts
new file mode 100644
index 0000000..1cd838c
--- /dev/null
+++ b/backend/src/domain/use-cases/auth/login-user.use-case.ts
@@ -0,0 +1,59 @@
+/**
+ * login-user.use-case.ts
+ * LoginUserUseCase: lógica para iniciar sesión.
+ * - Valida datos
+ * - Busca el usuario por email
+ * - Compara las contraseñas
+ * - Genera el JWT
+ */
+
+import { LoginUserDto, LoginUserDtoValidator } from "../../dtos/index.js";
+import { AuthRepository } from "../../repositories/auth.repository.js";
+import { CustomError } from "../../errors/custom.error.js";
+import { BcryptAdapter } from "../../../config/bcrypt.js";
+import { JwtAdapter } from "../../../config/jwt.js";
+
+export interface LoginUserResponse {
+  user: {
+    id: number;
+    email: string;
+    name: string;
+  };
+  token: string;
+}
+
+export class LoginUserUseCase {
+  constructor(private repository: AuthRepository) {}
+
+  async execute(data: unknown): Promise<LoginUserResponse> {
+    // Validar DTO
+    const dto = LoginUserDtoValidator.validate(data);
+
+    // Buscar usuario por email
+    const user = await this.repository.findByEmail(dto.email);
+    if (!user) {
+      throw CustomError.unauthorized("Invalid credentials");
+    }
+
+    // Comparar contraseñas
+    const isPasswordValid = await BcryptAdapter.compare(dto.password, user.password);
+    if (!isPasswordValid) {
+      throw CustomError.unauthorized("Invalid credentials");
+    }
+
+    // Generar JWT
+    const token = JwtAdapter.generate({
+      id: user.id,
+      email: user.email,
+    });
+
+    return {
+      user: {
+        id: user.id,
+        email: user.email,
+        name: user.name,
+      },
+      token,
+    };
+  }
+}
\ No newline at end of file
diff --git a/backend/src/domain/use-cases/auth/register-user.use-case.ts b/backend/src/domain/use-cases/auth/register-user.use-case.ts
new file mode 100644
index 0000000..cdd649c
--- /dev/null
+++ b/backend/src/domain/use-cases/auth/register-user.use-case.ts
@@ -0,0 +1,60 @@
+/**
+ * register-user.use-case.ts
+ * RegisterUserUseCase: lógica para registrar un usuario.
+ * - Valida datos
+ * - Verifica si el email ya existe
+ * - Hashea la contraseña
+ * - Crea el usuario
+ * - Genera el JWT
+ */
+
+import { RegisterUserDto, RegisterUserDtoValidator } from "../../dtos/index.js";
+import { AuthRepository } from "../../repositories/auth.repository.js";
+import { CustomError } from "../../errors/custom.error.js";
+import { BcryptAdapter } from "../../../config/bcrypt.js";
+import { JwtAdapter } from "../../../config/jwt.js";
+
+export interface RegisterUserResponse {
+  user: {
+    id: number;
+    email: string;
+    name: string;
+  };
+  token: string;
+}
+
+export class RegisterUserUseCase {
+  constructor(private repository: AuthRepository) {}
+
+  async execute(data: unknown): Promise<RegisterUserResponse> {
+    // Validar DTO
+    const dto = RegisterUserDtoValidator.validate(data);
+
+    // Verificar si el email ya existe
+    const existingUser = await this.repository.findByEmail(dto.email);
+    if (existingUser) {
+      throw CustomError.conflict("Email already in use");
+    }
+
+    // Hashear la contraseña
+    const hashedPassword = await BcryptAdapter.hash(dto.password);
+
+    // Crear el usuario
+    const user = await this.repository.create({
+      name: dto.name,
+      email: dto.email,
+      password: hashedPassword,
+    });
+
+    // Generar JWT
+    const token = JwtAdapter.generate({
+      id: user.id,
+      email: user.email,
+    });
+
+    return {
+      user,
+      token,
+    };
+  }
+}
diff --git a/backend/src/presentation/auth/controller.ts b/backend/src/presentation/auth/controller.ts
index b9c7b2b..3f9c941 100644
--- a/backend/src/presentation/auth/controller.ts
+++ b/backend/src/presentation/auth/controller.ts
@@ -1,137 +1,68 @@
-import { Request, Response } from "express";
-import bcrypt from "bcryptjs";
+/**
+ * controller.ts
+ * AuthController: maneja las peticiones HTTP de autenticación.
+ * - Recibe los datos
+ * - Llama al use-case correspondiente
+ * - Responde al cliente
+ * - Maneja los errores
+ */
 
-import { prisma } from "../../data/postgres/index.js";
-import { JwtAdapter } from "../../config/jwt.js";
-import { LoginUserDto, RegisterUserDto } from "../../domain/dtos/index.js";
+import { Response } from "express";
 import { AuthRequest } from "../middlewares/auth.middleware.js";
+import { CustomError } from "../../domain/errors/custom.error.js";
+import { AuthRepositoryImpl } from "../../data/repositories/auth.repository.impl.js";
+import { RegisterUserUseCase } from "../../domain/use-cases/auth/register-user.use-case.js";
+import { LoginUserUseCase } from "../../domain/use-cases/auth/login-user.use-case.js";
+import { GetMeUseCase } from "../../domain/use-cases/auth/get-me.use-case.js";
 
 export class AuthController {
+  private repository = new AuthRepositoryImpl();
+  private registerUseCase = new RegisterUserUseCase(this.repository);
+  private loginUseCase = new LoginUserUseCase(this.repository);
+  private getMeUseCase = new GetMeUseCase(this.repository);
 
-    // SIN metodos estaticos para hacer DI
-    constructor() {}
+  register = async (req: AuthRequest, res: Response) => {
+    try {
+      const result = await this.registerUseCase.execute(req.body);
+      res.status(201).json(result);
+    } catch (error) {
+      this.handleError(error, res);
+    }
+  };
 
-    public registerUser = async (req: Request, res: Response) => {
+  login = async (req: AuthRequest, res: Response) => {
+    try {
+      const result = await this.loginUseCase.execute(req.body);
+      res.status(200).json(result);
+    } catch (error) {
+      this.handleError(error, res);
+    }
+  };
 
-        const [error, registerUserDto] = RegisterUserDto.create(req.body);
+  getMe = async (req: AuthRequest, res: Response) => {
+    try {
+      if (!req.user) {
+        throw CustomError.unauthorized("User not authenticated");
+      }
 
-        if (error) {
-            return res.status(400).json({ error });
-        }
+      const result = await this.getMeUseCase.execute(req.user.id);
+      res.status(200).json(result);
+    } catch (error) {
+      this.handleError(error, res);
+    }
+  };
 
-        try {
-            const userExists = await prisma.user.findUnique({
-                where: {
-                    email: registerUserDto!.email,
-                }
-            });
-
-            if (userExists) {
-                return res.status(400).json({
-                    error: 'Email already exists'
-                });
-            }
-
-            const hashedPassword = bcrypt.hashSync(registerUserDto!.password, 10);
-
-            const user = await prisma.user.create({
-                data: {
-                    name: registerUserDto!.name,
-                    email: registerUserDto!.email,
-                    password: hashedPassword,
-                }
-            });
-
-            const token = JwtAdapter.generateToken({
-                id: user.id,
-                email: user.email,
-                role: user.role,
-            });
-
-            return res.status(201).json({
-                user: {
-                    id: user.id,
-                    name: user.name,
-                    email: user.email,
-                    role: user.role,
-                },
-                token
-            });
-
-        } catch (error) {
-            console.log(error);
-            return res.status(500).json({
-                error: 'Internal server error'
-            });
-        }
+  private handleError(error: unknown, res: Response): void {
+    if (error instanceof CustomError) {
+      res.status(error.statusCode).json({ error: error.message });
+      return;
     }
 
-    public loginUser = async (req: Request, res: Response) => {
-
-        const [error, loginUserDto] = LoginUserDto.create(req.body);
-
-        if (error) {
-            return res.status(400).json({ error });
-        }
-
-        try {
-            const user = await prisma.user.findUnique({
-                where: {
-                    email: loginUserDto!.email,
-                }
-            });
-
-            if (!user) {
-                return res.status(400).json({
-                    error: 'Invalid email or password'
-                });
-            }
-
-            const isPasswordValid = bcrypt.compareSync(
-                loginUserDto!.password,
-                user.password
-            );
-
-            if (!isPasswordValid) {
-                return res.status(400).json({
-                    error: 'Invalid email or password'
-                });
-            }
-
-            const token = JwtAdapter.generateToken({
-                id: user.id,
-                email: user.email,
-                role: user.role,
-            });
-
-            return res.json({
-                user: {
-                    id: user.id,
-                    name: user.name,
-                    email: user.email,
-                    role: user.role,
-                },
-                token
-            });
-
-        } catch (error) {
-            console.log(error);
-            return res.status(500).json({
-                error: 'Internal server error'
-            });
-        }
+    if (error instanceof Error) {
+      res.status(400).json({ error: error.message });
+      return;
     }
 
-    public getMe = async (req: AuthRequest, res: Response) => {
-
-        if (!req.user) {
-            return res.status(401).json({
-                error: 'User not authenticated'
-            });
-        }
-
-        return res.json({
-            user: req.user
-        });
-    }
+    res.status(500).json({ error: "Internal server error" });
+  }
 }
\ No newline at end of file
diff --git a/backend/src/presentation/auth/routes.ts b/backend/src/presentation/auth/routes.ts
index 2913c41..e8808d4 100644
--- a/backend/src/presentation/auth/routes.ts
+++ b/backend/src/presentation/auth/routes.ts
@@ -1,20 +1,22 @@
+/**
+ * routes.ts
+ * Rutas de autenticación.
+ * Define los endpoints de register, login y getMe.
+ */
+
 import { Router } from "express";
 import { AuthController } from "./controller.js";
 import { AuthMiddleware } from "../middlewares/auth.middleware.js";
 
 export class AuthRoutes {
+  static get routes(): Router {
+    const router = Router();
+    const controller = new AuthController();
 
-    static get routes(): Router {
+    router.post("/register", controller.register);
+    router.post("/login", controller.login);
+    router.get("/me", AuthMiddleware.validate, controller.getMe);
 
-        const router = Router();
-        const controller = new AuthController();
-
-        router.post('/register', controller.registerUser);
-        router.post('/login', controller.loginUser);
-
-        // Ruta protegida para probar JWT
-        router.get('/me', AuthMiddleware.validateJwt, controller.getMe);
-
-        return router;
-    }
+    return router;
+  }
 }
\ No newline at end of file
diff --git a/backend/src/presentation/middlewares/auth.middleware.ts b/backend/src/presentation/middlewares/auth.middleware.ts
index c1daaa4..a605845 100644
--- a/backend/src/presentation/middlewares/auth.middleware.ts
+++ b/backend/src/presentation/middlewares/auth.middleware.ts
@@ -1,46 +1,54 @@
-import { Request, Response, NextFunction } from "express";
-import { JwtAdapter } from "../../config/jwt.js";
+/**
+ * auth.middleware.ts
+ * Middleware para validar el JWT.
+ * - Lee el token del header Authorization: Bearer TOKEN
+ * - Valida el token
+ * - Busca el usuario en base de datos
+ * - Agrega el usuario a req.user
+ */
 
-interface TokenPayload {
-    id: number;
-    email: string;
-    role: string;
-}
+import { Request, Response, NextFunction } from "express";
+import { JwtAdapter, JwtPayload } from "../../config/jwt.js";
+import { AuthRepositoryImpl } from "../../data/repositories/auth.repository.impl.js";
+import { CustomError } from "../../domain/errors/custom.error.js";
 
 export interface AuthRequest extends Request {
-    user?: TokenPayload;
+  user?: JwtPayload;
 }
 
 export class AuthMiddleware {
+  static async validate(req: AuthRequest, res: Response, next: NextFunction) {
+    try {
+      // Obtener el token del header
+      const authHeader = req.headers.authorization;
+      if (!authHeader || !authHeader.startsWith("Bearer ")) {
+        throw CustomError.unauthorized("Missing or invalid Authorization header");
+      }
 
-    static validateJwt = (req: AuthRequest, res: Response, next: NextFunction) => {
+      const token = authHeader.substring(7); // Remover "Bearer "
 
-        const authorization = req.header('Authorization');
+      // Validar el token
+      const payload = JwtAdapter.validate(token);
+      if (!payload) {
+        throw CustomError.unauthorized("Invalid token");
+      }
 
-        if (!authorization) {
-            return res.status(401).json({
-                error: 'No token provided'
-            });
-        }
+      // Verificar que el usuario existe en BD
+      const repository = new AuthRepositoryImpl();
+      const user = await repository.findById(payload.id);
+      if (!user) {
+        throw CustomError.unauthorized("User not found");
+      }
 
-        if (!authorization.startsWith('Bearer ')) {
-            return res.status(401).json({
-                error: 'Invalid Bearer token'
-            });
-        }
+      // Agregar el usuario al request
+      req.user = payload;
 
-        const token = authorization.split(' ').at(1) ?? '';
-
-        const payload = JwtAdapter.validateToken<TokenPayload>(token);
-
-        if (!payload) {
-            return res.status(401).json({
-                error: 'Invalid token'
-            });
-        }
-
-        req.user = payload;
-
-        next();
+      next();
+    } catch (error) {
+      if (error instanceof CustomError) {
+        return res.status(error.statusCode).json({ error: error.message });
+      }
+      res.status(500).json({ error: "Internal server error" });
     }
+  }
 }
\ No newline at end of file
diff --git a/frontend/src/app/_layout.tsx b/frontend/src/app/_layout.tsx
index 7a02f47..f354518 100644
--- a/frontend/src/app/_layout.tsx
+++ b/frontend/src/app/_layout.tsx
@@ -11,12 +11,45 @@ export default function Layout() {
         tabBarInactiveTintColor: "#9CA3AF",
 
         tabBarStyle: {
-          height: 70,
-          paddingBottom: 10,
-          paddingTop: 10,
+          position: "absolute",
+          bottom: 5,
+          left: 20,
+          right: 20,
+
+          height: 82,
+
+          borderRadius: 25,
+
           backgroundColor: "#FFFFFF",
+
           borderTopWidth: 0,
-          elevation: 8,
+
+          shadowColor: "#000",
+          shadowOffset: {
+            width: 0,
+            height: 10,
+          },
+
+          shadowOpacity: 0.08,
+          shadowRadius: 10,
+
+          elevation: 10,
+
+          paddingHorizontal: 10,
+        },
+
+        tabBarLabelStyle: {
+          fontSize: 11,
+          fontWeight: "400",
+          marginBottom: 8,
+        },
+
+        tabBarItemStyle: {
+          paddingTop: 6,
+          paddingBottom: 4,
+          borderRadius: 18,
+          marginVertical: 6,
+          marginHorizontal: 4,
         },
       }}
     >
@@ -24,8 +57,12 @@ export default function Layout() {
         name="index"
         options={{
           title: "Inicio",
-          tabBarIcon: ({ color, size }) => (
-            <Ionicons name="home-outline" size={size} color={color} />
+          tabBarIcon: ({ focused, color }) => (
+            <Ionicons
+              name={focused ? "home" : "home-outline"}
+              size={focused ? 28 : 24}
+              color={color}
+            />
           ),
         }}
       />
@@ -34,8 +71,12 @@ export default function Layout() {
         name="alerts"
         options={{
           title: "Alertas",
-          tabBarIcon: ({ color, size }) => (
-            <Ionicons name="notifications-outline" size={size} color={color} />
+          tabBarIcon: ({ focused, color }) => (
+            <Ionicons
+              name={focused ? "notifications" : "notifications-outline"}
+              size={focused ? 28 : 24}
+              color={color}
+            />
           ),
         }}
       />
@@ -44,8 +85,12 @@ export default function Layout() {
         name="guide"
         options={{
           title: "Guía",
-          tabBarIcon: ({ color, size }) => (
-            <Ionicons name="leaf-outline" size={size} color={color} />
+          tabBarIcon: ({ focused, color }) => (
+            <Ionicons
+              name={focused ? "leaf" : "leaf-outline"}
+              size={focused ? 28 : 24}
+              color={color}
+            />
           ),
         }}
       />
@@ -54,8 +99,12 @@ export default function Layout() {
         name="profile"
         options={{
           title: "Perfil",
-          tabBarIcon: ({ color, size }) => (
-            <Ionicons name="person-outline" size={size} color={color} />
+          tabBarIcon: ({ focused, color }) => (
+            <Ionicons
+              name={focused ? "person" : "person-outline"}
+              size={focused ? 28 : 24}
+              color={color}
+            />
           ),
         }}
       />
diff --git a/frontend/src/app/guide.tsx b/frontend/src/app/guide.tsx
index fbdcea9..3561942 100644
--- a/frontend/src/app/guide.tsx
+++ b/frontend/src/app/guide.tsx
@@ -8,7 +8,7 @@ export default function GuideScreen() {
                 justifyContent: "center",
                 alignItems: "center",
             }}
-        >
+            >
         <Text>Guía</Text>
         </View>
     );
diff --git a/frontend/src/app/index.tsx b/frontend/src/app/index.tsx
index 4ef3629..752dd59 100644
--- a/frontend/src/app/index.tsx
+++ b/frontend/src/app/index.tsx
@@ -1,4 +1,4 @@
-/*import { View, Text, ScrollView } from "react-native";
+import { View, Text } from "react-native";
 
 export default function HomeScreen() {
   return (
@@ -12,91 +12,4 @@ export default function HomeScreen() {
       <Text>Inicio</Text>
     </View>
   );
-}*/
-
-import { View, ScrollView } from 'react-native';
-
-import EtaCard from '../components/EtaCard';
-import QuickAction from '../components/QuickAction';
-import SectionTitle from '../components/SectionTitle';
-import AlertItem from '../components/Alertltem';
-
-export default function Home() {
-  return (
-    <ScrollView
-      style={{ flex: 1, backgroundColor: '#ffffff' }}
-      showsVerticalScrollIndicator={false}
-    >
-
-      {/*ETA*/}
-      <EtaCard
-        minutes={12}
-        status="Camión en ruta 🚛"
-      />
-
-      {/*ACCIONES RÁPIDAS*/}
-      <SectionTitle title="Acciones rápidas" />
-
-      <View
-        style={{
-          flexDirection: 'row',
-          justifyContent: 'space-around',
-          paddingHorizontal: 10,
-          marginTop: 10,
-        }}
-      >
-        <QuickAction title="Mapa" icon="🗺️" />
-        <QuickAction title="Reportar" icon="🚨" />
-        <QuickAction title="Horarios" icon="🕒" />
-      </View>
-
-      {/*IMPACTO SEMANAL*/}
-      <SectionTitle title="Impacto semanal" />
-
-      <View
-        style={{
-          marginHorizontal: 15,
-          backgroundColor: '#F0F0F3',
-          padding: 20,
-          borderRadius: 16,
-        }}
-      >
-        <AlertItem
-          message="🚛 5 recolecciones completadas"
-          type="success"
-        />
-
-        <AlertItem
-          message="⏱ Sin retrasos esta semana"
-          type="success"
-        />
-
-        <AlertItem
-          message="📍 Cobertura completa en tu zona"
-          type="success"
-        />
-      </View>
-
-      {/* 🔔 ALERTAS RECIENTES */}
-      <SectionTitle title="Alertas recientes" />
-
-      <View style={{ marginBottom: 40 }}>
-        <AlertItem
-          message="🚛 Ruta iniciada"
-          type="success"
-        />
-
-        <AlertItem
-          message="📍 Camión cerca de tu zona"
-          type="warning"
-        />
-
-        <AlertItem
-          message="⏳ Retraso detectado"
-          type="danger"
-        />
-      </View>
-
-    </ScrollView>
-  );
 }
\ No newline at end of file
diff --git a/frontend/src/app/profile.tsx b/frontend/src/app/profile.tsx
index 23dee45..754f25d 100644
--- a/frontend/src/app/profile.tsx
+++ b/frontend/src/app/profile.tsx
@@ -4,12 +4,12 @@ export default function ProfileScreen() {
     return (
         <View
             style={{
-                    flex: 1,
-                    justifyContent: "center",
-                    alignItems: "center",
-                }}
-            >
-            <Text>Perfil</Text>
+                flex: 1,
+                justifyContent: "center",
+                alignItems: "center",
+            }}
+        >
+        <Text>Perfil</Text>
         </View>
     );
-}
\ No newline at end of file
+}