// about this tool

HTTP status codes are three-digit integers returned by a server to indicate the result of a client request. They are grouped into five classes: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client error), and 5xx (server error). This reference covers all codes defined in RFC 7231 and later RFCs, with plain-English explanations and common causes.

// when to use

Look up what a specific status code means while debugging an API response
Understand the difference between 301 and 302, or 401 and 403
Identify which error class a code belongs to at a glance
Check the meaning of less common codes like 409, 422, or 429

// faq

What is the difference between 401 and 403?

401 Unauthorized means the request lacks valid authentication credentials — the client should log in. 403 Forbidden means the server understood the request and knows who you are, but refuses to authorize the action.

What is the difference between 301 and 302?

301 Moved Permanently signals that the resource has been moved forever — browsers and search engines update their records. 302 Found is a temporary redirect; the original URL remains canonical.

// related tools

// about this tool

// when to use

// faq