API (Application Programming Interface) Design is the practice of creating interfaces that allow different software systems to communicate effectively, reliably, and intuitively. Well-designed APIs are consistent, predictable, easy to use, and hard to misuse. From RESTful principles and resource-oriented design to GraphQL queries, gRPC contracts, and event-driven APIs, modern API design is critical for microservices, mobile backends, and third-party integrations.

This API Design quiz online free features 200 expertly crafted questions: 70 Easy, 70 Hard, and 60 Advanced.

Why API Design Matters

APIs are the building blocks of modern software. Poorly designed APIs cause integration headaches, security vulnerabilities, and technical debt. Key topics include: RESTful principles (resources, HTTP methods, status codes, HATEOAS), API versioning strategies (URL path, custom header, content negotiation), OpenAPI/Swagger specification, API security (API keys, JWT, OAuth2, rate limiting), Pagination and filtering, Error handling and meaningful error responses, GraphQL (queries, mutations, subscriptions, resolvers, schema definition), gRPC (Protocol Buffers, service definition, streaming), Webhooks vs polling, API gateways, Idempotency, CORS, API documentation tools (Swagger UI, Redoc, Postman), API testing strategies, and API governance.

Career Benefits

API architects and developers earn $120,000-$200,000 annually. Expertise in API design is essential for backend roles, platform teams, and technical leadership positions.

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