| Category | Meaning | Description |
|---|---|---|
| 1xx | Informational | Request received, continuing process |
| 2xx | Success | Request successfully received, understood, and processed |
| 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 |
• 200 OK - Request succeeded, most common success response
• 201 Created - Resource created successfully, common for POST requests
• 204 No Content - Success with no content returned, common for DELETE
• 301 Moved Permanently - Permanent redirect, transfers SEO authority
• 302 Found - Temporary redirect
• 304 Not Modified - Resource unchanged, use browser cache
• 400 Bad Request - Malformed request syntax
• 401 Unauthorized - Authentication required
• 403 Forbidden - Authenticated but access denied
• 404 Not Found - Resource does not exist
• 429 Too Many Requests - Rate limit exceeded
• 500 Internal Server Error - Server-side error
• 502 Bad Gateway - Gateway error
• 503 Service Unavailable - Service temporarily unavailable
• 504 Gateway Timeout - Gateway timeout
This HTTP status code reference tool provides comprehensive search and filtering:
Search: Enter a status code (e.g., "404"), status name (e.g., "Not Found"), or keyword (e.g., "redirect") in the search box. The tool filters matching status codes in real-time, searching across codes, English names, and descriptions.
Category Filter: Click category buttons to filter by 1xx/2xx/3xx/4xx/5xx. Each category is color-coded for quick identification: green (1xx), cyan (2xx), yellow (3xx), orange (4xx), red (5xx).
View Details: Each status code card shows the code, name, category label, and detailed description. You can quickly browse the meaning and use case of all status codes.
API Development & Debugging: In RESTful API design, correctly using HTTP status codes is fundamental to good API design. 2xx indicates success, 4xx indicates client request errors, 5xx indicates server errors. Developers need to be familiar with various status code meanings to design standard API responses.
SEO & Website Optimization: Search engine crawlers use HTTP status codes to determine page status. 301 redirects transfer page authority, 404 error pages affect user experience, 503 tells crawlers to retry later during maintenance. Correct status code usage is crucial for SEO.
Operations Monitoring: DevOps engineers monitor HTTP status code distribution to assess system health. A spike in 4xx errors may indicate attacks or frontend bugs, while a spike in 5xx errors may indicate server overload or application faults.
Status Code Standards: HTTP status codes are maintained by IANA (Internet Assigned Numbers Authority) in a registry, defined across multiple RFC documents. Core status codes are defined in RFC 7231 (HTTP/1.1 Semantics and Content), with WebDAV extensions in RFC 4918.
Non-Standard Status Codes: Beyond official standards, some services and frameworks use non-standard codes (e.g., Cloudflare's 520-527, Twitter API's 429). This tool also includes common non-standard extension codes for reference.
RESTful API Best Practices: 200 for successful GET, 201 for successful POST creation, 204 for successful DELETE, 400 for request parameter errors, 401 for unauthenticated, 403 for no permission, 404 for resource not found, 409 for conflicts, 422 for validation failures, 429 for rate limiting, 500 for internal server errors.
HTTP status codes are three-digit response codes that a server returns in response to a client's HTTP request. The first digit indicates the response category: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error. Status codes help developers and browsers understand the result of a request.
404 indicates a client error — the requested resource does not exist on the server (Not Found). 500 indicates a server error — the server encountered an unexpected condition while processing the request (Internal Server Error). Simply put, 404 means 'what you're looking for doesn't exist' and 500 means 'the server has a problem'.
301 means permanent redirect (Moved Permanently) — search engines will update their index to the new URL, ideal for permanent URL changes. 302 means temporary redirect (Found) — search engines keep the original URL indexed, suitable for temporary jumps. For SEO, 301 is better for passing link authority.
The status codes in this tool are based on the official IANA HTTP Status Code Registry and RFC standards (RFC 7231, RFC 4918, RFC 7538, etc.), covering all officially registered status codes and common non-standard extension codes. All data is stored locally — no internet connection required.