HTTP Status Codes Reference

Look up any HTTP status code — what it means, when it is used, and how to handle it.

📖 Want the full story? Read our HTTP Status Codes Developer Guide — 4xx vs 5xx, API design rules, and a decision table.

HTTP Status Code Categories

1xx
Informational
Request received, processing continues.
2xx
Success
Request was received, understood, and accepted.
3xx
Redirection
Further action is needed to complete the request.
4xx
Client Error
The request contains bad syntax or cannot be fulfilled.
5xx
Server Error
The server failed to fulfil a valid request.

Frequently Asked Questions

What are HTTP status codes?

HTTP status codes are 3-digit numbers returned by a web server in response to a client request. The first digit defines the category: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error.

What is the difference between 301 and 302 redirects?

A 301 Moved Permanently tells search engines the URL has permanently moved — they transfer link equity and update their index. A 302 Found signals a temporary move — search engines keep the original URL indexed.

What is the difference between 401 and 403?

401 Unauthorized means the client must authenticate (authentication error — not logged in). 403 Forbidden means the server refuses to authorize the request (authorization error — logged in but no permission).

What is a 429 status code?

429 Too Many Requests indicates rate limiting. The response often includes a Retry-After header. Always implement exponential backoff when handling 429 responses in API clients.