REST API

REST API Best Practices

Resource Design

Use nouns for endpoints, not verbs: /users not /getUsers. Let HTTP methods convey the action: GET (read), POST (create), PUT (full replace), PATCH (partial update), DELETE (remove).

Use plural nouns for collections (/users), singular identifiers for items (/users/123). Nest resources for clear ownership: /users/123/orders for orders belonging to user 123. Avoid nesting deeper than two levels -- flatten with query parameters instead.

HTTP Status Codes

Return the correct status code -- clients depend on it for error handling:

• 200 for successful GET/PUT/PATCH
• 201 for successful POST (resource created)
• 204 for successful DELETE (no content)
• 400 for bad request (validation errors)
• 401 for unauthenticated
• 403 for unauthorized (authenticated but not allowed)
• 404 for not found
• 409 for conflict (duplicate, version mismatch)
• 422 for unprocessable entity (valid JSON, invalid semantics)
• 500 for server errors (never expose internals)

Request and Response Format

Use JSON for request and response bodies. Use camelCase for JSON field names (JavaScript convention) or snake_case (Python convention) -- be consistent within the API, never mix.

Return consistent error responses: {"error": "message", "code": "VALIDATION_FAILED", "details": [...]}. Clients should be able to parse errors programmatically, not just read human messages.

Pagination

Always paginate collection endpoints. Use cursor-based pagination (?cursor=abc123&limit=20) for large or frequently changing datasets. Include pagination metadata in the response: total, next_cursor, has_more.

Versioning

Version your API from day one: /api/v1/users. Use URL-based versioning for simplicity. Header-based versioning (Accept: application/vnd.api.v1+json) is cleaner but harder to test and debug.

Authentication

Use bearer tokens (JWT or opaque) in the Authorization header. Never pass tokens in URL query parameters -- they appear in logs and browser history. Use short-lived access tokens with refresh tokens for longer sessions.

Documentation

Maintain an OpenAPI specification (openapi.yaml). Generate it from code annotations or write it manually, but keep it in sync with the implementation. Stale API docs are worse than no docs -- they create false confidence.

Rate Limiting

Implement rate limiting on all public endpoints. Return 429 Too Many Requests with Retry-After header. Use sliding window counters, not fixed windows, to prevent burst abuse at window boundaries.

Source: calcosmic/Aether — distributed by TomeVault.