Free Online HTTP Status Code Lookup & Reference Guide
Comprehensive developer directory explaining standard REST and web HTTP response status codes with causes and debugging steps.
Direct Answer & Pipeline Overview
HTTP Status Code Lookup & Reference Guide is a specialized, 100% client-side engineering utility developed by Atlyxen Studios. It processes calculations and conversions directly inside your browser memory using hardware-accelerated WebAssembly and WebGL, guaranteeing instant results with zero server file transfers and zero data retention.
How to Use the HTTP Status Code Lookup & Reference Guide
Search Status Code or Symptom
Type any 3-digit status code or keyword such as timeout, gateway, cors, or redirect into the search box.
Filter by Category
Click category pills to filter between 2xx Success, 3xx Redirect, 4xx Client Errors, or 5xx Server Errors.
Inspect Diagnosis and Fixes
Read the technical summary, root causes, and recommended fixes to resolve issues in your web applications.
Key Technical Capabilities
Comprehensive catalog spanning 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client, and 5xx Server errors
Edge CDN error directory including Cloudflare 520, 521, 522, and 524 timeouts
Actionable debugging steps and root cause analysis for every error code
Instant keyword and numerical search with category pill filters
RFC 9110 specification references and HTTP caching indicators
One-click clipboard copy for code headers and explanations
Frequently Asked Questions
What is the fundamental difference between 401 Unauthorized and 403 Forbidden?
401 Unauthorized indicates that the client has not provided valid authentication credentials (e.g. missing or expired JWT token). 403 Forbidden means the identity of the user is known to the server, but the user lacks permission to access the resource.
What is the difference between 301 and 302 redirects for SEO?
A 301 Moved Permanently redirect signals search engines to pass link equity (PageRank) to the new destination URL. A 302 Found redirect is temporary and indicates that the original URL will be restored, so search engines do not transfer ranking power.
How do I fix a 502 Bad Gateway error?
A 502 Bad Gateway means your reverse proxy (NGINX, Cloudflare, or Apache) received an invalid response or connection drop from the upstream application. Check whether your Node.js, Python, or PHP process is crashed or exceeding server memory limits.
What does a 429 Too Many Requests status code mean?
HTTP 429 indicates that the client has exceeded the server rate limit within a given timeframe. API responses typically include a Retry-After header telling the client how many seconds to pause before retrying.