What Is a REST API?
A REST API is a standardized way for software systems to communicate over HTTP — using verbs (GET, POST, PUT, DELETE) and URLs to read and write resources.
REST (Representational State Transfer) is an architectural style for building APIs. It maps HTTP methods to CRUD operations, uses URLs to identify resources, and returns JSON (usually) as the response format.
The REST conventions:
| Method | URL | Meaning |
|---|---|---|
| GET | /users | List all users |
| GET | /users/42 | Get user with ID 42 |
| POST | /users | Create a new user |
| PUT | /users/42 | Replace user 42 |
| PATCH | /users/42 | Update fields on user 42 |
| DELETE | /users/42 | Delete user 42 |
Why REST is the default for SaaS APIs:
- Every HTTP client can call it — browser, mobile app, CLI, Postman
- Stateless — each request contains all information needed; no server-side session
- Cacheable — GET responses can be cached at the CDN
- Simple to understand and document
REST vs. GraphQL: REST is simpler to implement and cache. GraphQL gives clients exact control over what fields are returned — useful when many client types (web, mobile) have different data needs. For most SaaS MVPs, REST is faster to ship.
Supabase auto-generates a REST API: Supabase reads your Postgres schema and automatically generates REST endpoints for every table. Combined with RLS, you get a type-safe, access-controlled REST API without writing a single API handler.