HTTP Status Reference
Search, filter, and inspect RFC specifications, meanings, and fixes for HTTP response status codes.
All HTTP status code lookups execute client-side in browser memory.
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Filter & Search HTTP Status Codes
HTTP Status Directory (40 Statuses)
Comprehensive HTTP Response Status Code Reference
The HTTP Status Reference is an interactive technical encyclopedia of Hypertext Transfer Protocol (HTTP) response status codes. Covering standard codes from RFC 9110 (HTTP Semantics) alongside extended codes defined across specialized RFCs, the tool provides immediate explanations, operational contexts, and remediation steps for developers and system administrators.
HTTP status codes are three-digit integers issued by a web server in response to a client request. The first digit defines the response category: 1xx (Informational), 2xx (Successful), 3xx (Redirection), 4xx (Client Error), and 5xx (Server Error). Beyond defining standard definitions, this reference details crucial behavioral semantics including HTTP method idempotency, browser caching rules, and proxy handling constraints.
Built for rapid development troubleshooting, the interface allows real-time instant searching by code number, name, or keywords. Each status entry outlines typical trigger conditions, browser behavior, caching eligibility (heuristically cacheable vs no-store), and concrete debugging recommendations for both frontend and backend engineers.
Core Tool Capabilities
- Complete RFC Status Code Catalog: Covers every standard and extended HTTP status code across 1xx, 2xx, 3xx, 4xx, and 5xx categories with accurate definitions.
- Instant Real-Time Search: Filters codes dynamically by numeric digits, formal names, keyword concepts, or error symptoms for rapid lookup.
- Category Tab Filtering: Provides quick switching between Informational, Success, Redirection, Client Error, and Server Error groups.
- Caching and Idempotency Semantics: Explains whether a status code allows cache storage and how it interacts with GET, POST, PUT, and DELETE methods.
- Developer Remediation Guidance: Delivers actionable troubleshooting steps for resolving client-side and server-side HTTP errors quickly.
- Offline Interactive Reference: Runs entirely in local browser memory with zero network latency and no external API dependencies.
Local Browser Privacy
Your files are processed locally on your device. Files are not uploaded, transmitted, or stored on remote servers.
Once the page has loaded, you can disconnect your network connection and continue using this tool offline.
Target Use Cases
- • API Design and REST Development
- • Web Application Debugging
- • Search Engine Optimization Audits
- • DevOps and Infrastructure Monitoring
Technical Specifications & Platform Limits
Official Internet Engineering Task Force (IETF) HTTP specifications.
Complete coverage of official IANA status codes and common extensions.
Provides operational context, cache eligibility, and fix recommendations.
Matches status codes by number, phrase, keyword, and RFC reference.
Operates completely in local memory without server requests.
Step-by-Step Workflow
Search or Filter Status Codes
Enter a three-digit status code or keyword in the search bar, or select a category tab to view a specific group. Results update instantly.
Select a Status Code
Click on any status code card from the interactive list to open its comprehensive technical overview. Review the formal name and classification.
Review Semantics and RFC Details
Inspect the detailed definition, underlying RFC specification, caching behavior, and browser expectations. Check remediation guidance for errors.
Copy Code Reference
Click the copy button to copy the status code number, formal name, and summary to your clipboard for documentation or tickets.
Practical Real-World Use Cases
API Design and REST Development
Backend software engineers selecting the exact semantically correct HTTP status codes when designing RESTful APIs and microservices.
Web Application Debugging
Frontend developers diagnosing unexpected network failures, CORS preflight issues, and redirect loops in browser DevTools.
Search Engine Optimization Audits
Technical SEO specialists investigating 301 vs 302 redirect implementations, 404 broken links, and 503 server maintenance headers.
DevOps and Infrastructure Monitoring
Site reliability engineers interpreting server log anomalies, load balancer error rates, and CDN edge cache responses.
Frequently Asked Questions
- What is the difference between a 301 and a 302 redirect?
- A 301 Moved Permanently status informs browsers, proxies, and search engines that the requested resource has permanently moved to a new URL, instructing search engines to transfer link equity and clients to update bookmarks. A 302 Found (or 307 Temporary Redirect) indicates a temporary move, meaning clients should continue using the original URL for future requests without transferring search ranking equity.
- What is the difference between 401 Unauthorized and 403 Forbidden?
- A 401 Unauthorized response specifically indicates that the request lacks valid authentication credentials, and the response must include a WWW-Authenticate header challenging the client to authenticate. A 403 Forbidden response indicates that the server understood the client's identity, but refuses to authorize access because the user lacks necessary permissions, and re-authenticating with the same credentials will not change the outcome.
- Which HTTP status codes are cacheable by default?
- Under RFC 9110, responses with status codes 200 (OK), 203 (Non-Authoritative Information), 204 (No Content), 206 (Partial Content), 300 (Multiple Choices), 301 (Moved Permanently), 404 (Not Found), 405 (Method Not Allowed), 410 (Gone), 414 (URI Too Long), and 501 (Not Implemented) can be heuristically cached by default unless explicit Cache-Control headers dictate otherwise.
- What is the difference between a 502 Bad Gateway and a 504 Gateway Timeout?
- A 502 Bad Gateway error occurs when a server acting as a gateway or reverse proxy receives an invalid or malformed response from an upstream backend server. A 504 Gateway Timeout error occurs when the gateway or proxy server does not receive a response from the upstream server within its configured timeout window.
- Does this tool require an active internet connection to use?
- No. The HTTP Status Reference loads the complete RFC status catalog directly into your browser on page load. Once loaded, the search engine, filtering tabs, and diagnostic descriptions work completely offline without sending any data over the network.
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