HTTP Status Code Lookup
Search and inspect all official IANA HTTP response status codes (1xx, 2xx, 3xx, 4xx, 5xx) with technical explanations and debugging steps.
Quick Answer & Understanding Your Result
An HTTP Status Code Lookup tool provides instant technical explanations, root causes, and debugging solutions for all official IANA HTTP response status codes (1xx–5xx).
The 5 Standard HTTP Status Code Classes
- 1xx Informational: Request received, continuing process (e.g.
101 Switching Protocols). - 2xx Success: Action successfully received, understood, and accepted (e.g.
200 OK,201 Created,204 No Content). - 3xx Redirection: Further action required to complete request (e.g.
301 Moved Permanently,304 Not Modified). - 4xx Client Errors: Request contains bad syntax or cannot be fulfilled (e.g.
400 Bad Request,401 Unauthorized,403 Forbidden,404 Not Found). - 5xx Server Errors: Server failed to fulfill an apparently valid request (e.g.
500 Internal Server Error,502 Bad Gateway,503 Service Unavailable).
Type a status code or keyword above to inspect technical specifications and fixes instantly.
Formula & Calculation Logic
Technical Specification & ASTHTTP status classification:
- Groups 3-digit status codes into standardized 100-series semantic protocol classes defined by IANA.
Step-by-Step Guide
Enter Status Code or Search Term
Type a 3-digit number (e.g. 404, 502) or error keyword (e.g. timeout).
Instant IANA Specification Lookup
The engine retrieves RFC definitions and causes in 0ms.
Review Fixes & API Best Practices
Read actionable troubleshooting steps for clients and servers.
Worked Examples Table
| Example | Input Values | Calculated Result | Explanation |
|---|---|---|---|
| Status 404 Not Found | Retrieved RFC 9110 specification for HTTP 404. | ||
| 404 Not Found (Missing URL) | Provides instant quantitative evaluation for comparative practical analysis. |
Frequently Asked Questions
Evidence-Based Methodology & Authoritative References
IANA Hypertext Transfer Protocol (HTTP) Status Code Registry
IETF RFC 9110 - HTTP Semantics
Standard: ISO / W3C / IETF Authoritative Domain Standard
Formula: Status Class = Math.floor(code / 100) × 100
Last Reviewed: August 21, 2026
Primary Source: IANA Hypertext Transfer Protocol (HTTP) Status Code Registry
Reference Document: IETF RFC 9110 - HTTP Semantics
Computation Privacy: 100% client-side 0ms computation, zero data retention
All algorithms, formatters, and data conversions run 100% locally in your browser following official technical standards (RFC, ISO, W3C). Output should be verified prior to mission-critical production deployment.
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Calculated results are modeled based on standard scientific and mathematical formulas. Please verify with domain-specific technical documentation for specialized applications.