FreeBackend & APIs5.0 · 1 Api Study Note
A beginner-friendly APIs PDF study note covering the most important backend and full-stack interview concepts: REST APIs, HTTP methods, status codes, authentication, versioning, pagination, webhooks, rate limiting, and real-world API design. This guide is written for students, developers, and interview aspirants who want to understand how APIs work in real applications without getting lost in heavy theory. You will learn how clients and servers communicate, how API requests and responses are structured, how authentication works, and how production APIs are designed for reliability, security, scalability, and developer experience. Topics Covered 1. API Basics - What APIs are, why they exist, and how web/mobile apps use them. 2. REST APIs - Resources, endpoints, HTTP methods, request/response flow, and REST principles. 3. HTTP Methods And Status Codes - GET, POST, PUT, PATCH, DELETE, 200, 201, 400, 401, 403, 404, 500, and when to use each one. 4. API Authentication - API keys, bearer tokens, JWT, OAuth basics, cookies, and authorization headers. 5. API Design Best Practices - Pagination, filtering, sorting, validation, versioning, idempotency, rate limiting, and error responses. 6. Real-Life API Examples - User APIs, product APIs, order APIs, payment APIs, webhook flows, and interview-style explanation. What You Will Get 11-page detailed PDF guide Beginner-friendly API explanations Tables, code snippets, and request/response examples Interview-focused revision notes Real-world backend examples Best For Software engineering students, backend developers, full-stack developers, frontend developers learning APIs, and tech interview aspirants.
