Loading...
Loading...
Free online HTTP status code reference. Browse and search all HTTP response codes with descriptions and categories.
The server has received the request headers and the client should proceed to send the body.
The requester has asked the server to switch protocols.
Standard response for successful HTTP requests.
The request has been fulfilled and a new resource is created.
The server successfully processed the request but is not returning any content.
The requested resource has been permanently moved to a new URL.
The requested resource resides temporarily under a different URL.
The resource has not been modified since the last request.
The server cannot process the request due to client error.
Authentication is required and has failed or not been provided.
The server understood the request but refuses to authorize it.
The requested resource could not be found.
The request method is not supported for the requested resource.
The server timed out waiting for the request.
The user has sent too many requests in a given amount of time.
A generic error message when the server encounters an unexpected condition.
The upstream server returned an invalid response.
The server is temporarily unable to handle the request.
The upstream server failed to respond in time.
HTTP status codes are three-digit numbers returned by a server in response to a client's request. They are part of the HTTP/1.1 standard (RFC 7231) and are categorized into five classes based on the first digit. Each code conveys a specific meaning about the outcome of the request, helping developers and operations teams understand and diagnose web service behavior.
1xx (Informational) codes indicate that the server has received the request and is continuing to process it. These are provisional responses rarely seen by client applications. The most common is 101 Switching Protocols, used when upgrading to WebSocket connections.
2xx (Successful) codes indicate that the request was successfully received, understood, and accepted. The most familiar is 200 OK, the standard response for successful HTTP requests. 201 Created indicates a new resource was created (common in REST APIs), while 204 No Content is used when a request succeeds but returns no body, such as DELETE operations.
3xx (Redirection) codes tell the client that further action is needed to complete the request. 301 Moved Permanently and 302 Found are used for URL redirects, with 301 indicating the resource has permanently moved (search engines update their index) and 302 indicating a temporary move. 304 Not Modified enables efficient caching by telling the client the cached version is still valid.
4xx (Client Error) codes indicate the request contains bad syntax or cannot be fulfilled by the server. 400 Bad Request covers malformed requests, 401 Unauthorized requires authentication, 403 Forbidden means the server understood but refuses to authorize, and 404 Not Found is the most recognized error code on the web. 429 Too Many Requests is increasingly common for rate-limited APIs.
5xx (Server Error) codes indicate the server failed to fulfill a valid request. 500 Internal Server Error is a generic catch-all for unexpected server conditions. 502 Bad Gateway means an upstream server returned an invalid response. 503 Service Unavailable indicates the server is temporarily overloaded or down for maintenance. 504 Gateway Timeout means an upstream server failed to respond in time.
401 Unauthorized means the client must authenticate (log in) to access the resource. 403 Forbidden means the server understood the authentication but the authenticated user does not have permission to access the resource. 401 can be resolved by logging in; 403 cannot be resolved by the current user.
502 Bad Gateway means the server (acting as a gateway or proxy) received an invalid response from an upstream server. This often occurs when a web server (nginx) cannot reach an application server (Node.js, Python) or when the application crashes. It is typically temporary and may resolve on refresh.
404 errors are normal for any public website — they can result from broken links, users typing URLs incorrectly, or automated scanners probing for vulnerabilities. However, a sudden increase in 404s for specific paths may indicate a configuration issue, a broken redirect, or malicious scanning activity.