Standard HTTP Response Codes

Standard HTTP Status codes are issued by a server in response to a client’s request made to the server. When a call is made to a resource on the web, whether it’s a website or API, it will respond with a response code and any data the application expects. These codes are helpful in sending a high-level status to the calling application to determine the disposition of the call.

Informational Responses

Informational responses are rarely used for an API calls except for special circumstances.

Code	Name	Description
100	Continue	This interim response indicates that the client should continue the request or ignore the response if the request is already finished.
101	Switching Protocols	This code is sent in response to an Upgrade request header from the client and indicates the protocol the server is switching to.
102	Processing	This code indicates that the server has received and is processing the request, but no response is available yet.
103	Early Hints	This status code is primarily intended to be used with the Link header, letting the user agent start preloading resources while the server prepares a response or preconnect to an origin from which the page will need resources.

Successful Responses

Successful responses are used to indicate that the intended action was completed.

Code	Name	Description
200	OK	The request succeeded. The result meaning of “success” depends on the HTTP method: GET: The resource has been fetched and transmitted in the message body. PUT or POST: The resource describing the result of the action is transmitted in the message body.
201	Created	The request succeeded, and a new resource was created as a result. This is typically the response sent after POST requests, or some PUT requests.
202	Accepted	The request has been received but not yet acted upon. It is noncommittal, since there is no way in HTTP to later send an asynchronous response indicating the outcome of the request. It is intended for cases where another process or server handles the request, or for batch processing.
203	Non-Authoritative Information	The returned metadata is not exactly the same as is available from the origin server, but is collected from a local or a third-party copy. This is mostly used for mirrors or backups of another resource. Except for that specific case, the 200 OK response is preferred to this status.
204	No Content	There is no content to send for this request, but the headers may be useful. The user agent may update its cached headers for this resource with the new ones.
205	Reset Content	Tells the user agent to reset the document which sent this request.
206	Partial Content	This response code is used when the Range header is sent from the client to request only part of a resource.
207	Multi-Status (WebDAV)	Conveys information about multiple resources, for situations where multiple status codes might be appropriate.
208	Already Reported (WebDAV)	Used inside a <dav:propstat> response element to avoid repeatedly enumerating the internal members of multiple bindings to the same collection.
226	IM Used (HTTP Delta encoding)	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.

Redirection Messages

This indicates that the client must take additional action to complete the request. In a browser app, the browser may already have the redirect link to go to.

Code	Name	Description
300	Multiple Choices	The request has more than one possible response. The user agent or user should choose one of them. (There is no standardized way of choosing one of the responses, but HTML links to the possibilities are recommended so the user can pick.)
301	Moved Permanently	The URL of the requested resource has been changed permanently. The new URL is given in the response.
302	Found	This response code means that the URI of requested resource has been changed temporarily. Further changes in the URI might be made in the future. Therefore, this same URI should be used by the client in future requests.
303	See Other	The server sent this response to direct the client to get the requested resource at another URI with a GET request.
304	Not Modified	This is used for caching purposes. It tells the client that the response has not been modified, so the client can continue to use the same cached version of the response.
305	Use Proxy	Defined in a previous version of the HTTP specification to indicate that a requested response must be accessed by a proxy. It has been deprecated due to security concerns regarding in-band configuration of a proxy.
306	Unused	This response code is no longer used; it is just reserved. It was used in a previous version of the HTTP/1.1 specification.
307	Temporary Redirect	The server sends this response to direct the client to get the requested resource at another URI with the same method that was used in the prior request. This has the same semantics as the 302 Found HTTP response code, with the exception that the user agent must not change the HTTP method used: if a POST was used in the first request, a POST must be used in the second request.
308	Permanent Redirect	This means that the resource is now permanently located at another URI, specified by the Location: HTTP Response header. This has the same semantics as the 301 Moved Permanently HTTP response code, with the exception that the user agent must not change the HTTP method used: if a POST was used in the first request, a POST must be used in the second request.

Error Responses

Intended for situations where the error seems to have been caused by the client.

Code	Name	Description
400	Bad Request	The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).
401	Unauthorized	Although the HTTP standard specifies “unauthorized”, semantically this response means “unauthenticated”. That is, the client must authenticate itself to get the requested response.
402	Payment Required	This code’s initial purpose was for digital payment systems. However, this status code is rarely used, and no standard convention exists.
403	Forbidden	The request contained valid data and was understood by the server, but the server is refusing action. This may be due to the user not having the necessary permissions for a resource or needing an account of some sort, or attempting a prohibited action (e.g. creating a duplicate record where only one is allowed). This code is also typically used if the request provided authentication by answering the WWW-Authenticate header field challenge, but the server did not accept that authentication. The request should not be repeated.
404	Not Found	The server cannot find the requested resource. In the browser, this means the URL is not recognized. In an API, this can also mean that the endpoint is valid, but the resource does not exist. Servers may also send this response instead of 403 Forbidden to hide the existence of a resource from an unauthorized client. This response code is probably the most well-known due to its frequent occurrence on the web.
405	Method Not Allowed	The request method is known by the server but is not supported by the target resource. For example, an API may not allow calling DELETE to remove a resource.
406	Not Acceptable	This response is sent when the web server, after performing server-driven content negotiation, doesn’t find any content that conforms to the criteria given by the user agent.
407	Proxy Authentication Required	This is similar to 401 Unauthorized but authentication is needed to be done by a proxy.
408	Request Timeout	This response is sent on an idle connection by some servers, even without any previous request by the client. It means that the server would like to shut down this unused connection. This response is used much more since some browsers, like Chrome, Firefox 27+, or IE9, use HTTP pre-connection mechanisms to speed up surfing. Also note that some servers merely shut down the connection without sending this message.
409	Conflict	This response is sent when a request conflicts with the current state of the server.
410	Gone	This response is sent when the requested content has been permanently deleted from server, with no forwarding address. Clients are expected to remove their caches and links to the resource. The HTTP specification intends this status code to be used for “limited-time, promotional services”. APIs should not feel compelled to indicate resources that have been deleted with this status code.
411	Length Required	Server rejected the request because the Content-Length header field is not defined and the server requires it.
412	Precondition Failed	The client has indicated preconditions in its headers which the server does not meet.
413	Payload Too Large	Request entity is larger than limits defined by server. The server might close the connection or return an Retry-After header field.
414	URI Too Long	The URI requested by the client is longer than the server is willing to interpret.
415	Unsupported Media Type	The server does not support the media format of the requested data, so the server is rejecting the request.
416	Range Not Satisfiable	The range specified by the Range header field in the request cannot be fulfilled. It’s possible that the range is outside the size of the target URI’s data.
417	Expectation Failed	This response code indicates that the server cannot meet the expectation specified in the Expect request header field.
418	I’m a teapot	The server refuses the attempt to brew coffee with a teapot.
421	Misdirected Request	The request was directed at a server that was unable to produce a response. This can be sent by a server that is not configured to produce responses for the combination of scheme and authority that are included in the request URI.
422	Unprocessable Content (WebDAV)	The request was well-formed but was unable to be followed due to semantic errors.
423	Locked (WebDAV)	The resource that is being accessed is locked.
424	Failed Dependency (WebDAV)	The request failed due to failure of a previous request.
425	Too Early	Indicates that the server is unwilling to risk processing a request that might be replayed.
426	Upgrade Required	The server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol. The server sends an Upgrade header in a 426 response to indicate the required protocol(s).
428	Precondition Required	The origin server requires the request to be conditional. This response is intended to prevent the ‘lost update’ problem, where a client GETs a resource’s state, modifies it and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.
429	Too Many Requests	The user has sent too many requests in a given amount of time (“rate limiting”).
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 combined are too large.
451	Unavailable For Legal Reasons	The user agent requested a resource that cannot legally be provided, such as a web page censored by a government.

Server Error Responses

Indicate cases where the server knows it has encountered an error or cannot perform the request.

Code	Name	Description
500	Internal Server Error	The server has encountered a situation it cannot handle.
501	Not Implemented	The server does not support the requested method and cannot handle the request. The only methods that servers are required to support (and therefore that must not return this code) are GET and HEAD.
502	Bad Gateway	This error response indicates that the server, while acting as a gateway to obtain a response necessary to handle the request, received an invalid response.
503	Service Unavailable	The server is not ready to handle the request. Common causes are a server that is down for maintenance or that is overloaded. Note that together with this response, a user-friendly page explaining the problem should be sent. This response should be used for temporary conditions and the Retry-After HTTP header should, if possible, contain the estimated time before the recovery of the service. The webmaster must also take care about the caching-related headers that are sent along with this response, as these temporary condition responses should usually not be cached.
504	Gateway Timeout	This error response is given when the server is acting as a gateway and cannot get a response in time.
505	HTTP Version Not Supported	The server does not support the HTTP version used in the request.
506	Variant Also Negotiates	The server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, and is therefore not a proper end point in the negotiation process.
507	Insufficient Storage (WebDAV)	The method could not be performed on the resource because the server is unable to store the representation needed to successfully complete the request.
508	Loop Detected (WebDAV)	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. This code is considered obsolete.
511	Network Authentication Required	Indicates that the client needs to authenticate to gain network access.