The following is a list of commonly used HTTP status codes that a website can return. HTTP Status codes are returned by the server to the client software to determine the outcome of a request. These codes are valuable for SEO to determine if the page is returning the correct header code to Google and other search engines so they (the search engines) can crawl them properly and attribute metrics.
Codes 100-101 | Codes 200-206 | Codes 300-307 | Codes 400-417 | Codes 500-505
HTTP CODES – 100-101
100 – Continue
Tells the client that the first part of the request has been received and that it should continue with the rest of the request or ignore if the request has been fulfilled.
101 – Switching Protocols
Tells the client that the server will switch protocols to that specified in the Upgrade message header field during the current connection.
HTTP CODES 200-206
200 – OK
The request sent by the client was successful.
201 – Created
The request was successful and a new resource was created.
202 – Accepted
The request has been accepted for processing, but has not yet been processed.
203 – Non-Authoritative Information
The returned meta information in the entity-header is not the definitive set as available from the origin server.
204 – No Content
The request was successful but does not require the return of an entity-body.
205 – Reset Content
The request was successful but the User-Agent should reset the document view that caused the request.
206 – Partial Content
The partial GET request has been successful.
HTTP CODES 300-307
300 – Multiple Choices
The requested resource has multiple possibilities, each with different locations.
301 – Moved Permanently
The resource has permanently moved to a different URI.
302 – Found
The requested resource has been found under a different URI but the client should continue to use the original URI.
303 – See Other
The requested response is at a different URI and should be accessed using a GET command at the given URI.
304 – Not Modified
The resource has not been modified since the last request.
305 – Use Proxy
The requested resource can only be accessed through the proxy specified in the location field.
306 – No Longer Used
Reserved for future use.
307 – Temporary Redirect
The resource has temporarily been moved to a different URI. The client should use the original URI to access the resource in future as the URI may change.
HTTP CODES 400-417
400 – Bad Request
The syntax of the request was not understood by the server.
401 – Not Authorised
The request needs user authentication
402 – Payment Required
Reserved for future use.
403 – Forbidden
The server has refused to fulfill the request.
404 – Not Found
The document/file requested by the client was not found.
405 – Method Not Allowed
The method specified in the Request-Line is not allowed for the specified resource.
406 – Not Acceptable
The resource requested is only capable of generating response entities which have content characteristics not specified in the accept headers sent in the request.
407 – Proxy Authentication Required
The request first requires authentication with the proxy.
408 – Request Timeout
The client failed to sent a request in the time allowed by the server.
409 – Conflict
The request was unsuccessful due to a conflict in the state of the resource.
410 – Gone
The resource requested is no longer available and no forwarding address is available.
411 – Length Required
The server will not accept the request without a valid Content-Length header field.
412 – Precondition Failed
A precondition specified in one or more Request-Header fields returned false.
413 – Request Entity Too Large
The request was unsuccessful because the request entity is larger than the server will allow.
414 – Request URI Too Long
The request was unsuccessful because the URI specified is longer than the server is willing to process.
415 – Unsupported Media Type
The request was unsuccessful because the entity of the request is in a format not supported by the requested resource for the method requested.
416 – Requested Range Not Satisfiable
The request included a Range request-header field, and not any of the range-specifier values in this field overlap the current extent of the selected resource, and also the request did not include an If-Range request-header field.
417 – Expectation Failed
The expectation given in the Expect request-header could not be fulfilled by the server.
HTTP CODES 500-505
500 – Internal Server Error
The request was unsuccessful due to an unexpected condition encountered by the server.
501 – Not Implemented
The request was unsuccessful because the server can not support the functionality needed to fulfill the request.
502 – Bad Gateway
The server received an invalid response from the upstream server while trying to fulfill the request.
503 – Service Unavailable
The request was unsuccessful to the server being down or overloaded.
504 – Gateway Timeout
The upstream server failed to send a request in the time allowed by the server.
505 – HTTP Version Not Supported
The server does not support or is not allowing the HTTP protocol version specified in the request.