HTTP Status Codes Reference — 2xx, 3xx, 4xx & 5xx Diagnostic Guide

Standard response for successful HTTP requests (GET/POST/PUT)

Request succeeded and resulted in a new resource being created (POST/PUT)

Server successfully processed request but returns no response body (DELETE)

Target resource has been assigned a new permanent URI (transfers SEO link equity)

Temporary redirect (search engines will not transfer page rank)

Cached version is fresh and client can use cached resource directly without redownloading

Server cannot process request due to client syntax error or invalid payload

Authentication is required and has failed or has not yet been provided

Server understood request but refuses to authorize it (lacks permissions)

Server cannot find requested resource at the specified path

User has sent too many requests in a given time period (rate limited)

Generic error message when an unexpected condition occurred on the backend

Server acting as gateway/proxy received an invalid response from upstream backend

Server is currently unable to handle request due to temporary overloading or maintenance

Server acting as gateway/proxy did not receive a timely response from upstream server