The server has received the request headers and the client should proceed to send the request body.
Common Use Case:
Used in chunked transfer encoding
101Switching Protocols
Informational The requester has asked the server to switch protocols and the server has agreed to do so.
Common Use Case:
WebSocket upgrade from HTTP
102Processing
Informational The server has received and is processing the request, but no response is available yet.
Common Use Case:
WebDAV operations
103Early Hints
Informational Used to return some response headers before final HTTP message.
Common Use Case:
Preload resources while server prepares response
The request has succeeded. The meaning of success depends on the HTTP method used.
Common Use Case:
Standard response for successful HTTP requests
The request has been fulfilled and resulted in a new resource being created.
Common Use Case:
POST request successfully created a resource
The request has been accepted for processing, but the processing has not been completed.
Common Use Case:
Asynchronous processing, batch operations
203Non-Authoritative Information
Success The server is a transforming proxy that received a 200 OK from its origin, but is returning a modified version.
Common Use Case:
Proxy or cache modified the response
The server successfully processed the request and is not returning any content.
Common Use Case:
DELETE request succeeded, no response body needed
The server successfully processed the request, but is not returning any content and requires the requester to reset the document view.
Common Use Case:
Form submission, clear form after success
206Partial Content
Success The server is delivering only part of the resource due to a range header sent by the client.
Common Use Case:
Video streaming, resumable downloads
300Multiple Choices
Redirection Indicates multiple options for the resource from which the client may choose.
Common Use Case:
Multiple file formats available
301Moved Permanently
Redirection This and all future requests should be directed to the given URI.
Common Use Case:
Permanent URL change, SEO redirect
The resource is temporarily under a different URI.
Common Use Case:
Temporary redirect, URL shorteners
The response to the request can be found under another URI using a GET method.
Common Use Case:
Redirect after POST to prevent duplicate submissions
304Not Modified
Redirection Indicates that the resource has not been modified since the version specified by the request headers.
Common Use Case:
Browser caching, conditional requests
307Temporary Redirect
Redirection The request should be repeated with another URI but future requests should still use the original URI.
Common Use Case:
Temporary redirect preserving request method
308Permanent Redirect
Redirection The request and all future requests should be repeated using another URI.
Common Use Case:
Permanent redirect preserving request method
400Bad Request
Client Error The server cannot or will not process the request due to an apparent client error.
Common Use Case:
Invalid JSON, malformed request syntax
401Unauthorized
Client Error Authentication is required and has failed or has not yet been provided.
Common Use Case:
Missing or invalid authentication token
402Payment Required
Client Error Reserved for future use. Originally intended for digital payment systems.
Common Use Case:
Payment required for API access
The request was valid, but the server is refusing action. The user might not have the necessary permissions.
Common Use Case:
Insufficient permissions, IP blocked
The requested resource could not be found but may be available in the future.
Common Use Case:
Page doesn't exist, broken link
405Method Not Allowed
Client Error A request method is not supported for the requested resource.
Common Use Case:
POST to read-only endpoint
406Not Acceptable
Client Error The requested resource is capable of generating only content not acceptable according to the Accept headers.
Common Use Case:
Client requested unsupported format
407Proxy Authentication Required
Client Error The client must first authenticate itself with the proxy.
Common Use Case:
Corporate proxy requires authentication
408Request Timeout
Client Error The server timed out waiting for the request.
Common Use Case:
Client took too long to send request
Indicates that the request could not be processed because of conflict in the current state of the resource.
Common Use Case:
Version conflict, duplicate entry
Indicates that the resource requested is no longer available and will not be available again.
Common Use Case:
Permanently deleted resource
411Length Required
Client Error The request did not specify the length of its content, which is required by the requested resource.
Common Use Case:
Missing Content-Length header
412Precondition Failed
Client Error The server does not meet one of the preconditions that the requester put on the request.
Common Use Case:
If-Match header condition failed
413Payload Too Large
Client Error The request is larger than the server is willing or able to process.
Common Use Case:
File upload exceeds size limit
414URI Too Long
Client Error The URI provided was too long for the server to process.
Common Use Case:
URL exceeds maximum length
415Unsupported Media Type
Client Error The request entity has a media type which the server or resource does not support.
Common Use Case:
Wrong Content-Type header
416Range Not Satisfiable
Client Error The client has asked for a portion of the file, but the server cannot supply that portion.
Common Use Case:
Invalid byte range in Range header
417Expectation Failed
Client Error The server cannot meet the requirements of the Expect request-header field.
Common Use Case:
Expect: 100-continue not supported
418I'm a teapot
Client Error This code was defined in 1998 as an April Fools' joke and is not expected to be implemented by actual HTTP servers.
Common Use Case:
Easter egg, not for production use
421Misdirected Request
Client Error The request was directed at a server that is not able to produce a response.
Common Use Case:
HTTP/2 server cannot respond
422Unprocessable Entity
Client Error The request was well-formed but was unable to be followed due to semantic errors.
Common Use Case:
Validation errors in request body
The resource that is being accessed is locked.
Common Use Case:
WebDAV locked resource
424Failed Dependency
Client Error The request failed because it depended on another request and that request failed.
Common Use Case:
WebDAV dependency failed
Indicates that the server is unwilling to risk processing a request that might be replayed.
Common Use Case:
Prevent replay attacks
426Upgrade Required
Client Error The client should switch to a different protocol.
Common Use Case:
Force upgrade to TLS
428Precondition Required
Client Error The origin server requires the request to be conditional.
Common Use Case:
Prevent lost update problem
429Too Many Requests
Client Error The user has sent too many requests in a given amount of time.
Common Use Case:
Rate limiting, API throttling
431Request Header Fields Too Large
Client Error The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.
Common Use Case:
Headers exceed size limit
451Unavailable For Legal Reasons
Client Error A server operator has received a legal demand to deny access to a resource or to a set of resources.
Common Use Case:
Content blocked by government
500Internal Server Error
Server Error A generic error message when the server encounters an unexpected condition.
Common Use Case:
Unhandled exception, server crash
501Not Implemented
Server Error The server either does not recognize the request method, or it lacks the ability to fulfill the request.
Common Use Case:
Unsupported HTTP method
502Bad Gateway
Server Error The server was acting as a gateway or proxy and received an invalid response from the upstream server.
Common Use Case:
Upstream server error, proxy issue
503Service Unavailable
Server Error The server is currently unavailable (overloaded or down for maintenance).
Common Use Case:
Maintenance mode, server overload
504Gateway Timeout
Server Error The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.
Common Use Case:
Upstream server timeout
505HTTP Version Not Supported
Server Error The server does not support the HTTP protocol version used in the request.
Common Use Case:
Unsupported HTTP version
506Variant Also Negotiates
Server Error Transparent content negotiation for the request results in a circular reference.
Common Use Case:
Server configuration error
507Insufficient Storage
Server Error The server is unable to store the representation needed to complete the request.
Common Use Case:
WebDAV server out of space
508Loop Detected
Server Error The server detected an infinite loop while processing the request.
Common Use Case:
WebDAV infinite loop
510Not Extended
Server Error Further extensions to the request are required for the server to fulfill it.
Common Use Case:
Extension required
511Network Authentication Required
Server Error The client needs to authenticate to gain network access.
Common Use Case:
Captive portal, WiFi login