HTTP Status Code Cheat Sheet

A quick summary that runs through the most commonly used HTTP status codes by class.

So you don't have to look up the spec every time, we've gathered the status codes you most often run into in practice, grouped by class. Clicking each code in the list below takes you to a detail page covering its meaning, when it occurs, causes, and fixes.

Quick rules of thumb: 2xx is success, 3xx is a move (redirect), 4xx is a request (client) problem, and 5xx is a server problem. When you see a 4xx, check the request URL, headers, and authentication first; when you see a 5xx, check the server logs and backend state first.

Common status codes at a glance

2xxSuccess
200OK CommonThe request succeeded. The response body depends on the method used.201Created CommonThe request succeeded and a new resource was created as a result.204No Content CommonThe request succeeded but there is no content to return.
3xxRedirection
301Moved Permanently CommonThe resource has permanently moved to a new URL given in the Location header.302Found CommonThe resource temporarily resides at a different URL; keep using the original URL.304Not Modified CommonThe cached copy is still valid, so no body is sent.
4xxClient Error
400Bad Request CommonThe server cannot process the request due to a client error such as malformed syntax.401Unauthorized CommonAuthentication is required and has failed or not been provided (i.e. unauthenticated).403Forbidden CommonThe server understood the request but refuses to authorize it. Re-authenticating will not help.404Not Found CommonThe server cannot find the requested resource. The most well-known status code.405Method Not Allowed CommonThe HTTP method is known but not supported for the target resource.409Conflict CommonThe request conflicts with the current state of the resource.422Unprocessable Content CommonThe request is well-formed but has semantic errors (e.g. validation failed).429Too Many Requests CommonThe client has sent too many requests in a given time (rate limiting).
5xxServer Error
500Internal Server Error CommonA generic catch-all: the server hit an unexpected condition and could not complete the request.502Bad Gateway CommonA gateway or proxy received an invalid response from an upstream server.503Service Unavailable CommonThe server is temporarily unable to handle the request due to overload or maintenance.504Gateway Timeout CommonA gateway or proxy did not get a timely response from an upstream server.