HTTP Status Codes Reference
HTTP status codes indicate the result of a server's attempt to process an HTTP request. They are grouped into five classes by their first digit.
Status code classes
| Range | Class | Meaning |
|---|---|---|
| 1xx | Informational | Request received, continuing process |
| 2xx | Success | Request successfully received, understood, and accepted |
| 3xx | Redirection | Further action needed to complete the request |
| 4xx | Client Error | Request contains bad syntax or cannot be fulfilled |
| 5xx | Server Error | Server failed to fulfill a valid request |
Most commonly encountered codes
- 200 OK: standard success response
- 201 Created: resource created (POST/PUT)
- 301 Moved Permanently: SEO-friendly permanent redirect
- 302 Found: temporary redirect
- 304 Not Modified: cached version is still valid
- 400 Bad Request: malformed request syntax
- 401 Unauthorized: authentication required
- 403 Forbidden: authenticated but not authorized
- 404 Not Found: resource does not exist
- 429 Too Many Requests: rate limit exceeded
- 500 Internal Server Error: unhandled server exception
- 502 Bad Gateway: upstream server returned invalid response
- 503 Service Unavailable: server temporarily overloaded or down for maintenance