Glossary · web
REST API
Definition
REST (Representational State Transfer) is an architecture for designing web APIs over HTTP. Resources are URL-addressed (/users/123) and managed via HTTP methods (GET, POST, PUT, DELETE). Stateless, cache-friendly, browser-native; 80%+ of web APIs in 2026 are REST.
Detailed explanation
REST was defined by Roy Fielding in his 2000 PhD thesis. It has 6 principles: client-server separation, statelessness, cacheability, layered system, uniform interface, optional code-on-demand.
HTTP methods: GET (read), POST (create), PUT (full update), PATCH (partial update), DELETE. Status codes: 2xx (success), 3xx (redirect), 4xx (client error), 5xx (server error). 200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 404 Not Found, 500 Server Error are most common.
REST vs GraphQL: REST is endpoint-based (/users, /posts), GraphQL uses a single endpoint with a query language. REST is simpler, more cache-friendly, has wider tooling. GraphQL is more efficient on complex UIs, no over-fetching.
Use cases
→Web/mobile app backend API
→Microservices communicating over REST
→Public API (developer ecosystem)
→3rd party integration
Pros
- +Mature + standard (the web's lingua franca)
- +Cache-friendly (CDN edge cache)
- +Wide tooling (Postman, Swagger, OpenAPI)
- +Browser-native (fetch API)
Cons
- −Over-fetching (returns unused fields)
- −Multiple round-trips (1 page = 5-10 API calls)
- −Versioning complexity (v1, v2 maintained in parallel)
- −No type safety (solvable with JSON Schema or OpenAPI)
Related terms
Related services
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