HTTP 상태코드 치트시트

가장 자주 쓰는 HTTP 상태코드를 구간별로 빠르게 훑어보는 요약입니다.

매번 스펙을 찾지 않아도 되도록, 실무에서 가장 자주 마주치는 상태코드를 구간별로 모았습니다. 아래 목록의 각 코드를 누르면 의미·발생 상황·원인·해결 방법을 담은 상세 페이지로 이동합니다.

빠른 판단 기준: 2xx는 성공, 3xx는 이동(리다이렉트), 4xx는 요청(클라이언트) 문제, 5xx는 서버 문제입니다. 4xx가 보이면 요청 URL·헤더·인증을, 5xx가 보이면 서버 로그와 백엔드 상태를 먼저 확인하세요.

자주 쓰는 상태코드 한눈에 보기

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