How to Build API Security in NestJS?

Introduction

API security is crucial for modern web applications, ensuring that sensitive data is protected from unauthorized access, attacks, and misuse. NestJS, a progressive Node.js framework, provides built-in tools and best practices for securing APIs effectively. APIs are vulnerable to threats such as data breaches, unauthorized access, injection attacks, and denial-of-service (DoS) attacks without proper security measures.

In this guide, we’ll explore the key strategies for enhancing API security in NestJS and explain why each measure is essential.

1. Authentication with JWT

Why Use JWT?

Authentication is the first line of defense in securing an API. JSON Web Tokens (JWT) provide a stateless and scalable solution for authentication. Unlike traditional session-based authentication, JWT does not require storing session data on the server, making it an ideal choice for distributed applications. Each token is self-contained and includes user information, expiration time, and a cryptographic signature to prevent tampering.

Implementing JWT in NestJS

1. Install required packages:

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    npm install @nestjs/jwt @nestjs/passport passport passport-jwt
   

2. Create an AuthModule:

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    @Module({
      imports: [
        JwtModule.register({
          secret: process.env.JWT_SECRET || 'secretKey',
          signOptions: { expiresIn: '1h' },
        }),
      ],
      providers: [AuthService],
    })
    export class AuthModule {}
   

3. Implement JWT strategy:

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    @Injectable()
    export class JwtStrategy extends PassportStrategy(Strategy) {
      constructor(private readonly authService: AuthService) {
        super({
          jwtFromRequest: ExtractJwt.fromAuthHeaderAsBearerToken(),
          secretOrKey: process.env.JWT_SECRET || 'secretKey',
        });
      }
      async validate(payload: any) {
        return { userId: payload.sub, username: payload.username };
      }
    }