What is API Design?
The practice of planning and structuring the endpoints, data formats, authentication, and conventions of an Application Programming Interface so it's consistent, intuitive, and maintainable.
In plain English
API design is like designing a restaurant menu. A well-organized menu groups items logically, uses clear names, includes descriptions, and follows a consistent format. A poorly designed menu is confusing, inconsistent, and makes customers order the wrong thing.
How it works
Good API design involves choosing a paradigm (REST, GraphQL, RPC), defining resource naming conventions, selecting appropriate HTTP methods and status codes, structuring request/response formats, implementing versioning, and documenting everything. It's about creating a contract between your backend and every client that consumes it — frontend apps, mobile apps, third-party integrations.
Why it matters for AI-built apps
AI tools generate APIs quickly but often inconsistently — mixing naming conventions, using wrong HTTP methods (POST for everything), returning inconsistent response formats, and lacking pagination or error handling. Poor API design creates compounding problems: every frontend feature becomes harder to build, mobile integration becomes painful, and third-party developers can't use your API reliably.
Common issues
Inconsistent naming (camelCase mixed with snake_case), using POST for read operations, not using proper HTTP status codes (returning 200 for errors), missing pagination on list endpoints, no API versioning, inconsistent error response formats, deeply nested response objects, and no rate limiting or authentication.
Best practices
Follow REST conventions: use nouns for resources (GET /users, not GET /getUsers), appropriate HTTP methods, and standard status codes. Version your API from day one (v1/). Return consistent response shapes including error formats. Implement pagination, filtering, and sorting on list endpoints. Document your API with OpenAPI/Swagger. Design for the consumer's needs, not your database structure.
Frequently asked questions
My AI tool generated a bunch of API endpoints — how do I know if they're well-designed?
Check for consistency: Are naming conventions uniform? Do all endpoints use correct HTTP methods (GET for reading, POST for creating, PUT/PATCH for updating, DELETE for deleting)? Do they return consistent error formats? Do list endpoints support pagination? If you find inconsistencies, a refactoring pass to standardize your API is well worth the investment.
Should I use REST or GraphQL?
For most startups, REST is the simpler and more battle-tested choice. GraphQL shines when you have multiple frontends (web, mobile, third-party) with different data needs, or when over-fetching/under-fetching is a real problem. Don't choose GraphQL just because it sounds modern — it adds complexity. Start with REST and migrate specific endpoints to GraphQL if needed.
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