100Continue1xx
The server has received the request headers and the client should proceed to send the request body.
Anwendungsfall:Large file uploads — server confirms it will accept the data before the client sends the body.
101Switching Protocols1xx
The server is switching protocols as requested by the client via the Upgrade header.
Anwendungsfall:WebSocket connections — upgrading from HTTP to WebSocket protocol.
102Processing1xx
The server has received and is processing the request, but no response is available yet.
Anwendungsfall:Long-running WebDAV requests to prevent client timeout.
103Early Hints1xx
Used to return some response headers before the final HTTP message.
Anwendungsfall:Preloading resources (CSS, JS) while server prepares the full response.
200OK2xx
The request has succeeded. The meaning depends on the HTTP method used.
Anwendungsfall:Standard successful GET request returning requested data.
201Created2xx
The request has been fulfilled and a new resource has been created.
Anwendungsfall:POST request that creates a new user account or database record.
202Accepted2xx
The request has been accepted for processing, but processing is not complete.
Anwendungsfall:Async job queues — request accepted, processing happens in background.
203Non-Authoritative Information2xx
The returned metadata is not exactly the same as available from the origin server.
Anwendungsfall:Proxy or CDN returning cached/modified headers from upstream.
204No Content2xx
The server successfully processed the request but is not returning any content.
Anwendungsfall:DELETE request — resource removed, nothing to return.
205Reset Content2xx
The server successfully processed the request and asks the client to reset the document view.
Anwendungsfall:Form submission — tells browser to clear/reset the form.
206Partial Content2xx
The server is delivering only part of the resource due to a range header.
Anwendungsfall:Video streaming — serving byte ranges for seek/resume.
207Multi-Status2xx
Conveys information about multiple resources where multiple status codes might be appropriate.
Anwendungsfall:WebDAV batch operations with mixed success/failure results.
208Already Reported2xx
Members of a DAV binding have already been enumerated and are not included again.
Anwendungsfall:WebDAV avoiding duplicate enumeration in recursive responses.
226IM Used2xx
The server has fulfilled a GET request with instance-manipulations applied.
Anwendungsfall:Delta encoding — server sends only changes since last request.
300Multiple Choices3xx
The request has more than one possible response; the user or agent should choose one.
Anwendungsfall:Content negotiation — multiple formats available (JSON, XML, HTML).
301Moved Permanently3xx
The resource has been permanently moved to a new URI.
Anwendungsfall:Domain migration — old URL permanently redirects to new one. SEO-friendly.
302Found3xx
The resource is temporarily located at a different URI.
Anwendungsfall:Temporary redirect during maintenance or A/B testing.
303See Other3xx
The response can be found at another URI using GET.
Anwendungsfall:POST/redirect/GET pattern — redirect after form submission.
304Not Modified3xx
The resource has not been modified since the last request.
Anwendungsfall:Browser cache validation — ETag/If-Modified-Since checks.
305Use Proxy3xx
The requested resource must be accessed through a proxy. (Deprecated)
Anwendungsfall:Deprecated — was used to force proxy usage.
307Temporary Redirect3xx
The resource is temporarily at another URI; method and body must not change.
Anwendungsfall:HTTPS upgrade — redirect HTTP to HTTPS preserving POST method.
308Permanent Redirect3xx
The resource has permanently moved; method and body must not change.
Anwendungsfall:API versioning — permanently redirect old API endpoint to new one.
400Bad Request4xx
The server cannot process the request due to client error (malformed syntax, invalid framing).
Anwendungsfall:Malformed JSON body, missing required fields, invalid query params.
401Unauthorized4xx
The request requires user authentication. The client must authenticate itself.
Anwendungsfall:API call without auth token or with expired JWT.
402Payment Required4xx
Reserved for future use. Sometimes used for digital payment systems.
Anwendungsfall:Paywall — resource requires payment (Stripe integration).
403Forbidden4xx
The server understood the request but refuses to authorize it.
Anwendungsfall:User authenticated but lacks permission (role-based access).
404Not Found4xx
The server cannot find the requested resource.
Anwendungsfall:Requesting a deleted resource or mistyped URL.
405Method Not Allowed4xx
The HTTP method is not supported for the target resource.
Anwendungsfall:Sending PUT to a read-only endpoint that only accepts GET.
406Not Acceptable4xx
The server cannot produce a response matching the Accept headers.
Anwendungsfall:Client requests XML but server only serves JSON.
407Proxy Authentication Required4xx
Authentication with an intermediary proxy is required.
Anwendungsfall:Corporate proxy requiring credentials before forwarding.
408Request Timeout4xx
The server timed out waiting for the request from the client.
Anwendungsfall:Client opened connection but never sent data within time limit.
409Conflict4xx
The request conflicts with the current state of the server.
Anwendungsfall:Creating a user with an email that already exists.
410Gone4xx
The resource is no longer available and will not be available again.
Anwendungsfall:Deliberately removed API endpoint — stronger than 404.
411Length Required4xx
The server requires the Content-Length header to be defined.
Anwendungsfall:Upload endpoint requiring Content-Length for resource allocation.
412Precondition Failed4xx
One or more conditions in the request headers evaluated to false.
Anwendungsfall:Conditional update with If-Match that doesn't match current ETag.
413Payload Too Large4xx
The request entity is larger than the server is willing to process.
Anwendungsfall:File upload exceeding max size (e.g., 10MB limit).
414URI Too Long4xx
The URI requested by the client is longer than the server will interpret.
Anwendungsfall:GET request with extremely long query string.
415Unsupported Media Type4xx
The media format of the requested data is not supported by the server.
Anwendungsfall:Sending application/xml to an endpoint that only accepts JSON.
416Range Not Satisfiable4xx
The range specified in the Range header cannot be fulfilled.
Anwendungsfall:Requesting bytes 1000-2000 of a 500-byte file.
417Expectation Failed4xx
The expectation indicated by the Expect header cannot be met.
Anwendungsfall:Server cannot meet Expect: 100-continue requirement.
418I'm a Teapot4xx
The server refuses to brew coffee because it is, permanently, a teapot.
Anwendungsfall:Easter egg. Defined in RFC 2324 (Hyper Text Coffee Pot Control Protocol).
421Misdirected Request4xx
The request was directed at a server that is not able to produce a response.
Anwendungsfall:HTTP/2 connection reuse to wrong virtual host.
422Unprocessable Entity4xx
The request was well-formed but semantically incorrect.
Anwendungsfall:Valid JSON but business logic validation fails (e.g., end date before start).
423Locked4xx
The resource that is being accessed is locked.
Anwendungsfall:WebDAV file locked by another user for editing.
424Failed Dependency4xx
The request failed due to failure of a previous request.
Anwendungsfall:WebDAV batch operation where a prerequisite step failed.
425Too Early4xx
The server is unwilling to risk processing a request that might be replayed.
Anwendungsfall:TLS 1.3 early data (0-RTT) that server won't process due to replay risk.
426Upgrade Required4xx
The server refuses to perform the request using the current protocol.
Anwendungsfall:Server requires TLS — client must upgrade from HTTP to HTTPS.
428Precondition Required4xx
The server requires the request to be conditional.
Anwendungsfall:Server requires If-Match header to prevent lost update problem.
429Too Many Requests4xx
The user has sent too many requests in a given amount of time.
Anwendungsfall:Rate limiting — API returns this with Retry-After header.
431Request Header Fields Too Large4xx
The server is unwilling to process the request because headers are too large.
Anwendungsfall:Oversized cookies or too many custom headers.
451Unavailable For Legal Reasons4xx
The resource is unavailable due to legal demands (censorship, court order).
Anwendungsfall:Content blocked by government order or DMCA takedown.
500Internal Server Error5xx
The server encountered an unexpected condition that prevented it from fulfilling the request.
Anwendungsfall:Unhandled exception in server code — generic catch-all error.
501Not Implemented5xx
The server does not support the functionality required to fulfill the request.
Anwendungsfall:HTTP method not implemented (e.g., PATCH on legacy server).
502Bad Gateway5xx
The server received an invalid response from an upstream server.
Anwendungsfall:Nginx/load balancer cannot reach the application server.
503Service Unavailable5xx
The server is currently unable to handle the request due to overload or maintenance.
Anwendungsfall:Planned maintenance or server overload — use with Retry-After.
504Gateway Timeout5xx
The server did not receive a timely response from an upstream server.
Anwendungsfall:Reverse proxy timeout — backend took too long to respond.
505HTTP Version Not Supported5xx
The server does not support the HTTP version used in the request.
Anwendungsfall:Client using HTTP/3 on a server that only supports HTTP/1.1.
506Variant Also Negotiates5xx
Transparent content negotiation results in a circular reference.
Anwendungsfall:Misconfigured content negotiation on server.
507Insufficient Storage5xx
The server is unable to store the representation needed to complete the request.
Anwendungsfall:WebDAV server ran out of disk space.
508Loop Detected5xx
The server detected an infinite loop while processing the request.
Anwendungsfall:WebDAV infinite loop in resource binding.
510Not Extended5xx
Further extensions to the request are required for the server to fulfill it.
Anwendungsfall:Server requires additional HTTP extension not provided.
511Network Authentication Required5xx
The client needs to authenticate to gain network access.
Anwendungsfall:Captive portal — hotel/airport WiFi login page.