HTTP Status Codes
Three-digit codes returned by servers indicating the result of an HTTP request.
Definition
HTTP status codes are three-digit numbers returned by web servers in response to HTTP requests. They indicate whether the request was successful, needs redirection, or encountered an error. Status codes are grouped into five classes: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client errors), and 5xx (server errors). Understanding status codes is essential for monitoring and debugging web applications.
Examples
Common Status Codes
The most frequently encountered HTTP status codes.
| Code | Name | Meaning |
|------|-----------------------|----------------------------------|
| 200 | OK | Request succeeded |
| 201 | Created | Resource created successfully |
| 301 | Moved Permanently | Resource moved to new URL |
| 302 | Found (Temporary) | Temporary redirect |
| 400 | Bad Request | Invalid request syntax |
| 401 | Unauthorized | Authentication required |
| 403 | Forbidden | Access denied |
| 404 | Not Found | Resource doesn't exist |
| 429 | Too Many Requests | Rate limit exceeded |
| 500 | Internal Server Error | Server-side error |
| 502 | Bad Gateway | Invalid upstream response |
| 503 | Service Unavailable | Server temporarily unavailable |
| 504 | Gateway Timeout | Upstream server timeout |Use Cases
Best Practices
- Monitor for 5xx errors (server problems)
- Alert on unexpected status codes
- Track 4xx rates to identify broken links or abuse
- Use appropriate codes in your own APIs
FAQ
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