HTTP status code guide

The short answer

HTTP status codes describe how a server handled a request: success, redirection, client error, or server error.

Step by step

1. Check a URL with HTTP Status Checker.
2. Read the status code together with the redirect chain and response timing.
3. Use the code's class and the server logs to choose the next diagnostic step.

Technical details

• 200 means success; 201 resource created; 301 and 302 redirects; 304 unchanged cached content; 400 bad request; 401 authentication required; 403 forbidden; 404 not found; 405 method not allowed; 408 request timeout; 429 rate limited; 500 server error; 502 bad gateway; 503 unavailable; 504 gateway timeout.

Common mistakes

• Treating every 3xx as an error.
• Calling a 404 a server outage without checking the requested path.
• Retrying 429 responses aggressively.

Limitations

• A single response is a point-in-time observation and cannot establish availability over time.