This module covers building web applications and APIs with Node.js. From raw HTTP servers and Express.js frameworks to real-time WebSockets and GraphQL — you’ll learn the patterns and practices used by every major Node.js web application in production.

Knowing Node.js fundamentals isn’t enough. This module bridges the gap between runtime knowledge and production web development — routing, middleware, validation, auth, file handling, real-time communication, and API design patterns.

flowchart LR
    REST["3.1 Building REST APIs"] --> Express["3.2 Express.js Framework"]
    Express --> Validation["3.3 Input Validation"]
    Validation --> Uploads["3.4 File Uploads"]
    Uploads --> Auth["3.5 Authentication & Security"]
    Auth --> WS["3.6 WebSockets & Real-Time"]
    WS --> GraphQL["3.7 GraphQL"]

    style REST fill:#4f46e5,color:#fff
    style Express fill:#7c3aed,color:#fff
    style Auth fill:#dc2626,color:#fff
    style GraphQL fill:#10b981,color:#fff

Common questions: REST vs GraphQL, JWT vs sessions, middleware patterns, CORS, rate limiting, WebSocket scaling.