| 200 |
OK |
Successful GET, PUT, PATCH |
| 201 |
Created |
Successful POST |
| 204 |
No Content |
Successful DELETE |
| 301 |
Moved Permanently |
Old URL should redirect to new URL |
| 304 |
Not Modified |
Caching: resource has not changed since last request |
| 400 |
Bad Request |
Malformed JSON, missing required fields |
| 401 |
Unauthorized |
Missing or expired auth token |
| 403 |
Forbidden |
Valid token, but insufficient permissions |
| 404 |
Not Found |
Non-existent resource |
| 405 |
Method Not Allowed |
POST to a GET-only endpoint |
| 409 |
Conflict |
Duplicate creation (unique constraint) |
| 422 |
Unprocessable Entity |
Valid JSON but invalid data (e.g., email format) |
| 429 |
Too Many Requests |
Rate limit exceeded |
| 500 |
Internal Server Error |
Unhandled exception on the server |
| 502 |
Bad Gateway |
Backend service is down |
| 503 |
Service Unavailable |
Server overloaded or under maintenance |