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HTTP Status Codes Reference - Complete Guide to HTTP Response Codes

HTTP Status Codes Reference

Complete searchable reference for all HTTP status codes and their meanings.

1xx Informational
Code Name Description
100 Continue The server has received the request headers and the client should proceed to send the request body.
101 Switching Protocols The requester has asked the server to switch protocols and the server has agreed to do so.
102 Processing The server has received and is processing the request, but no response is available yet.
103 Early Hints Used to return some response headers before final HTTP message.
2xx Success
Code Name Description
200 OK The request has succeeded. The meaning of the success depends on the HTTP method.
201 Created The request has been fulfilled and resulted in a new resource being created.
202 Accepted The request has been accepted for processing, but the processing has not been completed.
203 Non-Authoritative Information The returned metainformation is from a local or third-party copy, not from the origin server.
204 No Content The server successfully processed the request but is not returning any content.
205 Reset Content The server successfully processed the request, but is not returning any content and requires the requester to reset the document view.
206 Partial Content The server is delivering only part of the resource due to a range header sent by the client.
207 Multi-Status The message body that follows is an XML message and can contain a number of separate response codes.
208 Already Reported The members of a DAV binding have already been enumerated in a previous reply to this request.
226 IM Used The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.
3xx Redirection
Code Name Description
300 Multiple Choices Indicates multiple options for the resource that the client may follow.
301 Moved Permanently The resource has been moved permanently to a new URI, and all future requests should use the new URI.
302 Found The resource resides temporarily under a different URI.
303 See Other The response to the request can be found under a different URI using a GET method.
304 Not Modified The resource has not been modified since the version specified by the request headers.
305 Use Proxy The requested resource must be accessed through the proxy given by the Location field.
307 Temporary Redirect The request should be repeated with another URI but future requests should still use the original URI.
308 Permanent Redirect The request and all future requests should be repeated using another URI.
4xx Client Error
Code Name Description
400 Bad Request The server cannot or will not process the request due to a client error (e.g., malformed request syntax).
401 Unauthorized Authentication is required and has failed or has not yet been provided.
402 Payment Required Reserved for future use. Originally intended for digital payment systems.
403 Forbidden The server understood the request but refuses to authorize it.
404 Not Found The requested resource could not be found but may be available in the future.
405 Method Not Allowed The request method is not supported for the requested resource.
406 Not Acceptable The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request.
407 Proxy Authentication Required The client must first authenticate itself with the proxy.
408 Request Timeout The server timed out waiting for the request.
409 Conflict The request could not be processed because of conflict in the current state of the resource.
410 Gone The resource is no longer available and will not be available again.
411 Length Required The request did not specify the length of its content, which is required by the requested resource.
412 Precondition Failed The server does not meet one of the preconditions specified in the request.
413 Payload Too Large The request is larger than the server is willing or able to process.
414 URI Too Long The URI provided was too long for the server to process.
415 Unsupported Media Type The request entity has a media type which the server or resource does not support.
416 Range Not Satisfiable The client has asked for a portion of the file, but the server cannot supply that portion.
417 Expectation Failed The server cannot meet the requirements of the Expect request-header field.
418 I'm a teapot This code was defined in 1998 as an April Fools' joke. It is not expected to be implemented by actual HTTP servers.
421 Misdirected Request The request was directed at a server that is not able to produce a response.
422 Unprocessable Entity The request was well-formed but was unable to be followed due to semantic errors.
423 Locked The resource that is being accessed is locked.
424 Failed Dependency The request failed due to failure of a previous request.
425 Too Early The server is unwilling to risk processing a request that might be replayed.
426 Upgrade Required The client should switch to a different protocol.
428 Precondition Required The origin server requires the request to be conditional.
429 Too Many Requests The user has sent too many requests in a given amount of time.
431 Request Header Fields Too Large The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.
451 Unavailable For Legal Reasons The server is denying access to the resource as a consequence of a legal demand.
5xx Server Error
Code Name Description
500 Internal Server Error A generic error message when the server encounters an unexpected condition.
501 Not Implemented The server either does not recognize the request method, or it lacks the ability to fulfill the request.
502 Bad Gateway The server was acting as a gateway or proxy and received an invalid response from the upstream server.
503 Service Unavailable The server is currently unavailable (overloaded or down for maintenance).
504 Gateway Timeout The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.
505 HTTP Version Not Supported The server does not support the HTTP protocol version used in the request.
506 Variant Also Negotiates Transparent content negotiation for the request results in a circular reference.
507 Insufficient Storage The server is unable to store the representation needed to complete the request.
508 Loop Detected The server detected an infinite loop while processing the request.
510 Not Extended Further extensions to the request are required for the server to fulfill it.
511 Network Authentication Required The client needs to authenticate to gain network access.

Understanding HTTP Status Codes

HTTP status codes are three-digit numbers returned by servers to indicate the result of a client's request. They're divided into five categories.

Status Code Categories:

1xx Informational

The request was received and is being processed. These are provisional responses.

  • 100 Continue: Server received request headers, client should send body
  • 101 Switching Protocols: Server is switching protocols as requested
2xx Success

The request was successfully received, understood, and accepted.

  • 200 OK: Standard success response
  • 201 Created: Resource created successfully
  • 204 No Content: Success with no response body
3xx Redirection

Further action must be taken to complete the request.

  • 301 Moved Permanently: Resource permanently moved to new URL
  • 302 Found: Resource temporarily at different URL
  • 304 Not Modified: Cached version is still valid
4xx Client Error

The request contains bad syntax or cannot be fulfilled by the server.

  • 400 Bad Request: Malformed request syntax
  • 401 Unauthorized: Authentication required
  • 403 Forbidden: Server refuses to authorize
  • 404 Not Found: Resource doesn't exist
  • 429 Too Many Requests: Rate limit exceeded
5xx Server Error

The server failed to fulfill a valid request.

  • 500 Internal Server Error: Generic server error
  • 502 Bad Gateway: Invalid response from upstream server
  • 503 Service Unavailable: Server temporarily unavailable
  • 504 Gateway Timeout: Upstream server timeout

Common Use Cases by Status Code:

RESTful API Design:
  • GET request success: 200 OK
  • POST create resource: 201 Created
  • PUT/PATCH update: 200 OK or 204 No Content
  • DELETE resource: 200 OK or 204 No Content
  • Validation error: 400 Bad Request or 422 Unprocessable Entity
  • Unauthorized: 401 Unauthorized
  • Forbidden: 403 Forbidden
  • Not found: 404 Not Found

Status Code Decision Tree:

Is the request valid?
├─ No → 4xx Client Error (400, 401, 403, 404, etc.)
└─ Yes → Did the server process it successfully?
    ├─ No → 5xx Server Error (500, 502, 503, etc.)
    └─ Yes → Does it need redirection?
        ├─ Yes → 3xx Redirection (301, 302, 304, etc.)
        └─ No → 2xx Success (200, 201, 204, etc.)

Fun Facts:

  • 418 I'm a teapot: April Fools' joke from 1998, part of Hyper Text Coffee Pot Control Protocol
  • 451 Unavailable For Legal Reasons: Named after Fahrenheit 451 (book burning)
  • Most common: 200 (OK), 404 (Not Found), and 500 (Internal Server Error)

Testing Status Codes:

Use httpbin.org to test different status codes:

curl https://httpbin.org/status/200  # Returns 200 OK
curl https://httpbin.org/status/404  # Returns 404 Not Found
curl https://httpbin.org/status/500  # Returns 500 Internal Server Error

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