Status code groups
1xx informational
The request is still in progress. These are uncommon in normal browser debugging.
2xx success
The request succeeded. 200, 201, and 204 show up most often.
3xx redirection
The client needs to follow another URL or use cached content.
4xx client error
The request was invalid, unauthorized, missing, or rate-limited.
5xx server error
The server failed while trying to handle a valid request.
Common codes you actually use
| Code | Meaning | Typical case |
|---|---|---|
| 200 | OK | Normal successful GET or POST response |
| 201 | Created | Resource created successfully after POST |
| 301 | Moved Permanently | URL changed permanently, update links and canonical targets |
| 302 | Found | Temporary redirect, often login or short-term routing |
| 400 | Bad Request | Malformed payload or missing required parameter |
| 401 | Unauthorized | Missing or invalid authentication |
| 403 | Forbidden | Authenticated but not allowed to access this resource |
| 404 | Not Found | Route, file, or resource does not exist |
| 429 | Too Many Requests | Rate limit exceeded |
| 500 | Internal Server Error | Unhandled server-side failure |
Fast debug checklist
- If the code is 4xx, check the request first: auth, payload shape, URL, headers.
- If the code is 5xx, check the server and logs first.
- If the code is 301 or 302, verify where the redirect lands and whether that behavior is intended.
- If the code is 429, add retry logic or backoff instead of hammering the endpoint.
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