What is HTTP Status Codes Reference?
HTTP Status Codes Reference is a comprehensive, searchable guide to every standard HTTP response status code. HTTP status codes are three-digit numbers returned by a web server to indicate the result of a client request. They are grouped into five categories: 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, and 5xx Server Error. Understanding these codes is essential for web developers, API designers, DevOps engineers, and anyone debugging network requests. This reference covers all standard codes with detailed explanations, real-world use cases, and practical context for each one.
How to Use This Tool
Search by status code number or name using the search bar at the top. Filter by category using the category pills to focus on Informational, Success, Redirection, Client Error, or Server Error codes. Click any status code card to expand it and view the detailed explanation along with common use cases. The tool loads instantly with no external requests, making it a fast reference you can bookmark and use daily during development and debugging.
Common Use Cases
- Quickly looking up the meaning of a status code encountered in browser DevTools or server logs
- Choosing the correct status code to return from your API endpoints
- Debugging redirect chains, authentication failures, and CORS issues
- Learning the differences between similar codes like 401 vs 403 or 301 vs 308
Why Use a Client-Side Tool?
This reference is entirely self-contained and runs in your browser with no network requests. All status code data is embedded in the page, so it loads instantly and works offline. There is no tracking, no API calls, and no account required. Bookmark this page for a reliable, always-available HTTP status code reference that works even without an internet connection.
Frequently Asked Questions
What is the difference between 401 Unauthorized and 403 Forbidden?
401 Unauthorized means the request lacks valid authentication credentials. Providing correct credentials (like a valid API key or login token) will grant access. 403 Forbidden means the server understood the request and knows who you are, but refuses to authorize the action. Re-authenticating will not help because the issue is permissions, not identity.
When should I use 301 vs 302 vs 307 redirects?
Use 301 for permanent URL changes where you want search engines to update their index. Use 302 for temporary redirects where the original URL should remain indexed. Use 307 when you need a temporary redirect that preserves the HTTP method (POST stays POST). For permanent redirects that preserve the method, use 308.
What does a 502 Bad Gateway error mean?
A 502 error means a server acting as a gateway or proxy received an invalid response from an upstream server. Common causes include the upstream application server being down, a timeout between the reverse proxy and the application, or a misconfigured load balancer. Check the upstream server health and connection settings to resolve the issue.