What is the difference between HTTP status codes 401 and 403?

HTTP 401 generally indicates missing valid authentication, while 403 indicates that the server refuses the request. Investigate credentials for 401 and permissions or access rules for 403. The status alone does not identify the complete cause, so also inspect the response content, authentication flow, and server logs. This lookup explains common meanings rather than proving how a particular application chose to map its internal error to a response.

What error categories do HTTP 404 and 500 belong to?

HTTP 404 belongs to the client-error category, while 500 belongs to the server-error category. The first digits 4 and 5 identify those groups, but do not conclusively assign responsibility for the underlying problem. Check the request path, deployment state, and logs during diagnosis. This reference page lists common code meanings and does not send a request to a website to discover its current response status.

Does the HTTP status code tool check a website in real time?

This page is an HTTP status reference table and does not request an entered website. You can look up common meanings such as 200 for success and 301 for a permanent redirect. The locally maintained entries are not a live complete registry. Use an appropriate request inspection tool to observe an actual site's response, including headers and redirect behavior, rather than treating a lookup result as a connectivity check.

HTTP status codes

Reference of HTTP status codes (1xx–5xx)

Computed in your browser

Filter by code or a meaning keyword. Standard English reason phrases remain unchanged; their explanations follow the selected language.

Category

Filter

Code	Reason	Meaning
100	Continue	Interim response; the client should continue with the request.
101	Switching Protocols	The server is switching protocols as requested.
200	OK	Standard success response.
201	Created	Request succeeded and a new resource was created.
202	Accepted	Request accepted for processing but not yet completed.
204	No Content	Success with no response body.
206	Partial Content	Server delivered part of a resource (range request).
301	Moved Permanently	Resource has permanently moved to another URL.
302	Found	Resource is temporarily at a different URL.
303	See Other	Client should GET the URL supplied in Location.
304	Not Modified	Cached copy is still fresh; no body returned.
307	Temporary Redirect	Same as 302 but preserves method.
308	Permanent Redirect	Same as 301 but preserves method.
400	Bad Request	Request could not be understood or was malformed.
401	Unauthorized	Authentication is required or has failed.
403	Forbidden	Server understood but refuses to authorize.
404	Not Found	The resource was not found.
405	Method Not Allowed	HTTP method not allowed for this resource.
406	Not Acceptable	Server cannot produce a representation matching Accept headers.
408	Request Timeout	Client took too long to send the request.
409	Conflict	Request conflicts with server state.
410	Gone	Resource is no longer available and will not be back.
411	Length Required	Content-Length header is required.
412	Precondition Failed	A precondition given in the headers evaluated to false.
413	Payload Too Large	Request body exceeds the server’s limits.
414	URI Too Long	Request URI is longer than the server can process.
415	Unsupported Media Type	Media type of the request body is not supported.
416	Range Not Satisfiable	Requested range cannot be served.
418	I’m a teapot	Playful status defined by RFC 2324.
422	Unprocessable Content	Request is well-formed but semantically invalid.
425	Too Early	Server unwilling to process a request that might be replayed.
428	Precondition Required	The origin server requires the request to be conditional.
429	Too Many Requests	Client is being rate-limited.
431	Request Header Fields Too Large	Headers exceed the server’s limits.
451	Unavailable For Legal Reasons	Access denied for legal reasons.
500	Internal Server Error	Unexpected server error.
501	Not Implemented	Server does not recognise the request method.
502	Bad Gateway	Upstream server returned an invalid response.
503	Service Unavailable	Server temporarily unable to handle the request.
504	Gateway Timeout	Upstream did not respond in time.
505	HTTP Version Not Supported	HTTP version is not supported.
511	Network Authentication Required	Client needs to authenticate to gain network access.

Example

Input

Example result

404 · Not Found

Type a number or keyword to filter the table.

Technical details & limits

The first digit gives the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error and 5xx server error. Codes summarize outcomes; headers, bodies and server logs explain the cause. This is a curated local list, not a live registry or a URL status checker.

About this tool

Filter common HTTP response codes by number, phrase or description. Understand success, redirection, client errors and server errors when debugging APIs or reading logs.

Use cases

Look up whether a server error is client-side (4xx) or server-side (5xx).
Pick the right status code when writing an API.
Diagnose 502 / 504 responses from a CDN or reverse proxy.

How to use

Type a status code or keyword into the search box.
You can also narrow by class, from 1xx to 5xx.
The table filters live and the line below shows how many rows matched.

Notes

This page covers commonly-used codes, not the complete list (WebDAV 207/423 and similar are omitted). See the IANA HTTP Status Code Registry for the full set.

FAQ

What is the difference between HTTP status codes 401 and 403?: HTTP 401 generally indicates missing valid authentication, while 403 indicates that the server refuses the request. Investigate credentials for 401 and permissions or access rules for 403. The status alone does not identify the complete cause, so also inspect the response content, authentication flow, and server logs. This lookup explains common meanings rather than proving how a particular application chose to map its internal error to a response.
What error categories do HTTP 404 and 500 belong to?: HTTP 404 belongs to the client-error category, while 500 belongs to the server-error category. The first digits 4 and 5 identify those groups, but do not conclusively assign responsibility for the underlying problem. Check the request path, deployment state, and logs during diagnosis. This reference page lists common code meanings and does not send a request to a website to discover its current response status.
Does the HTTP status code tool check a website in real time?: This page is an HTTP status reference table and does not request an entered website. You can look up common meanings such as 200 for success and 301 for a permanent redirect. The locally maintained entries are not a live complete registry. Use an appropriate request inspection tool to observe an actual site's response, including headers and redirect behavior, rather than treating a lookup result as a connectivity check.

Related tools

HTTP status codes · Reference of HTTP status codes (1xx–5xx) — HTTP status codes — Tool illustration · dayeku.com