Updated June 26, 2026

HTTP status codes

HTTP status codes are three-digit responses a server returns for each request. The first digit sets the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, and 5xx server error.

1xx — Informational

The request was received and the process is continuing.

Code	Name	Meaning
`100`	Continue	The client should continue sending the request body.
`101`	Switching Protocols	The server agrees to switch protocols, for example to WebSocket.
`103`	Early Hints	Sends preliminary headers so the browser can start preloading resources.

2xx — Success

The request was received, understood, and accepted.

Code	Name	Meaning
`200`	OK	Standard success response with a body.
`201`	Created	The request succeeded and a new resource was created.
`202`	Accepted	Accepted for processing, but not yet completed.
`204`	No Content	Success with no response body to return.
`206`	Partial Content	Part of the resource is returned, used for range requests and resumable downloads.

3xx — Redirection

Further action is needed to complete the request.

Code	Name	Meaning
`301`	Moved Permanently	The resource has a new permanent URL; update links and bookmarks.
`302`	Found	Temporary redirect; the original URL should still be used in future.
`303`	See Other	Redirect to another URL using a GET request, often after a form POST.
`304`	Not Modified	The cached copy is still valid; no body is sent.
`307`	Temporary Redirect	Like 302, but the method and body must not change.
`308`	Permanent Redirect	Like 301, but the method and body must not change.

4xx — Client error

The request was malformed or not allowed.

Code	Name	Meaning
`400`	Bad Request	The server could not understand the request, often a syntax error.
`401`	Unauthorized	Authentication is required and has failed or is missing.
`403`	Forbidden	Authenticated but not allowed to access the resource.
`404`	Not Found	The resource does not exist at this URL.
`405`	Method Not Allowed	The HTTP method is not supported for this resource.
`409`	Conflict	The request conflicts with the current state, such as a version clash.
`410`	Gone	The resource was deliberately removed and will not return.
`422`	Unprocessable Content	The request was well-formed but failed validation.
`429`	Too Many Requests	The client has sent too many requests and is being rate limited.

5xx — Server error

The server failed to fulfil a valid request.

Code	Name	Meaning
`500`	Internal Server Error	A generic, unexpected server-side failure.
`501`	Not Implemented	The server does not support the functionality required.
`502`	Bad Gateway	An upstream server returned an invalid response.
`503`	Service Unavailable	The server is overloaded or down for maintenance.
`504`	Gateway Timeout	An upstream server did not respond in time.

301 vs 302Use 301 when a URL has moved for good so search engines transfer ranking to the new address. Use 302 or 307 for a temporary move where the original URL should keep its value.

References

Questions

What is the difference between 401 and 403?

401 Unauthorized means you are not authenticated, so logging in may help. 403 Forbidden means you are authenticated but still not allowed, so logging in will not change anything.

Is 404 a server error?

No. 404 is a 4xx client error: the request reached the server fine, but the resource does not exist at that URL.