33 status codes documented with examples

Complete HTTP Status Codes Reference

Look up any HTTP response code. Understand what it means, why it happens, and how to fix it.

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Status Code Categories

HTTP responses are grouped into five categories. Click any category to explore its codes.

1xx

Informational

2 codes

2xx

Success

5 codes

3xx

Redirection

6 codes

4xx

Client Error

14 codes

5xx

Server Error

6 codes

Tools & Guides

Free tools and resources for debugging HTTP issues, checking redirects, and monitoring your website.

HTTP Status Codes Cheat Sheet
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HTTP Status Checker
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Redirect Checker
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Broken Link Checker
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SSL Certificate Checker
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Quick Reference

Click any status code for a detailed explanation, troubleshooting guide, and real HTTP examples.

101 Switching Protocols 103 Early Hints 200 OK 201 Created 202 Accepted 204 No Content 206 Partial Content 301 Moved Permanently 302 Found 303 See Other 304 Not Modified 307 Temporary Redirect 308 Permanent Redirect 400 Bad Request 401 Unauthorized 403 Forbidden 404 Not Found 405 Method Not Allowed 408 Request Timeout 409 Conflict 410 Gone 413 Payload Too Large 415 Unsupported Media Type 418 I'm a Teapot 422 Unprocessable Entity 429 Too Many Requests 451 Unavailable For Legal Reasons 500 Internal Server Error 501 Not Implemented 502 Bad Gateway 503 Service Unavailable 504 Gateway Timeout 511 Network Authentication Required

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Frequently Asked Questions

Quick answers to common HTTP status code questions.

HTTP status codes are 3-digit numbers returned by a web server in response to a browser's request. They indicate whether the request was successful (2xx), redirected (3xx), caused a client error (4xx), or triggered a server error (5xx). For example, 200 means OK, 404 means Not Found, and 500 means Internal Server Error.
The 5 types (classes) of HTTP status codes are: 1xx Informational (request received, processing continues), 2xx Success (request successfully received and accepted), 3xx Redirection (further action needed to complete request), 4xx Client Error (request contains bad syntax or cannot be fulfilled), and 5xx Server Error (server failed to fulfill a valid request). Each class groups related response behaviors together.
The most common HTTP status code is 200 OK, which means the request was successful. Other frequently encountered codes include 301 (Moved Permanently) for redirects, 404 (Not Found) for missing pages, 304 (Not Modified) for cached content, and 500 (Internal Server Error) for server-side failures.
There are approximately 63 officially registered HTTP status codes defined by IANA across the five categories (1xx through 5xx). However, servers can return any 3-digit code, and some non-standard codes are widely used (e.g., 418 I'm a Teapot, 520-527 Cloudflare errors). HTTP Tiger documents 33 of the most commonly encountered status codes with detailed explanations and troubleshooting guides.
HTTP status code 0 is not an official HTTP status code. It typically indicates that no response was received at all -- the request failed before the server could respond. Common causes include CORS blocking, network errors, DNS resolution failure, the request being aborted by the client, or a browser extension interfering with the request. Check the browser developer console for more specific error details. Read the full guide on status code 0.
401 Unauthorized means the request lacks valid authentication credentials -- the user has not logged in or provided an API key. Re-authenticating may fix the issue. 403 Forbidden means the server understood the request and the user's identity, but the user does not have permission to access the resource. Re-authenticating will NOT help with a 403 because the server has already identified you and denied access based on your permissions.
A 301 redirect is permanent -- search engines transfer link equity to the new URL and update their index. A 302 redirect is temporary -- search engines keep the original URL indexed. Use 301 for permanent URL changes like site migrations or HTTPS upgrades, and 302 for temporary situations like A/B testing or maintenance pages.
To fix a 500 error: 1) Check your server error logs for specific details. 2) Review recent code changes or deployments. 3) Verify file permissions are correct. 4) Check for syntax errors in configuration files like .htaccess. 5) Ensure your server has sufficient memory and disk space. 6) Test database connectivity.
A 502 Bad Gateway error occurs when a server acting as a gateway or proxy receives an invalid response from an upstream server. Common causes include: the upstream server crashing or being overloaded, firewall rules blocking communication, PHP-FPM process timeouts, or network issues between servers. These errors are often temporary.
The http-status-codes npm package is a JavaScript/TypeScript library that provides constants and utility functions for HTTP status codes in Node.js projects. While useful for programmatic access, HTTP Tiger offers a more comprehensive free alternative for looking up status codes -- with detailed explanations, common causes, troubleshooting steps, and real-world examples that go far beyond simple constant definitions. No installation required.
You can check HTTP status codes online for free using HTTP Tiger (httptiger.com). Enter any URL to see its HTTP response status code, response headers, redirect chain, and response time. HTTP Tiger also offers bulk URL checking, broken link scanning, and SSL certificate verification -- all free to use with no account required.
A redirect checker is a tool that traces the full chain of HTTP redirects from an initial URL to its final destination. It shows each hop in the redirect chain along with the status code (301, 302, 307, 308) and response headers at each step. This is essential for SEO audits, debugging redirect loops, and verifying that URL migrations are configured correctly. Try the free redirect checker at httptiger.com.
Use a website monitoring service like HTTP Tiger to continuously check your site's HTTP status. Monitoring services send requests to your URLs at regular intervals and alert you when errors occur, helping you fix issues before your users notice them.