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HTTP status codes
A searchable reference for every common HTTP status code. Type to search by number or name, or filter by class. Everything runs in your browser.
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100
Continue
1xxThe initial part of the request was received and the client should continue sending the body. Sent in response to an Expect: 100-continue header.
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101
Switching Protocols
1xxThe server is switching protocols as the client requested with an Upgrade header, for example to a WebSocket connection.
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102
Processing
1xxA WebDAV interim response that tells the client the server has accepted the request but is still processing it.
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103
Early Hints
1xxSent before the final response so the browser can start preloading resources, typically via Link headers, while the server prepares the page.
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200
OK
2xxThe request succeeded. The meaning depends on the method: a GET returns the resource, a POST returns the result of the action.
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201
Created
2xxThe request succeeded and a new resource was created, usually after a POST or PUT. The new URL is typically returned in the Location header.
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202
Accepted
2xxThe request was accepted for processing but has not finished. Used for asynchronous work where the outcome is not yet known.
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203
Non-Authoritative Information
2xxThe request succeeded but the returned metadata came from a transforming proxy rather than the origin server.
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204
No Content
2xxThe request succeeded but there is no body to return. Common for a DELETE or a form submission that needs no new page.
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205
Reset Content
2xxThe request succeeded and the client should reset the document view, for example clearing a form for another entry.
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206
Partial Content
2xxOnly part of the resource is returned, in response to a Range header. Used for resumable downloads and media streaming.
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207
Multi-Status
2xxA WebDAV response that carries multiple status codes for different parts of a single request, encoded in an XML body.
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208
Already Reported
2xxA WebDAV code used inside a Multi-Status body to avoid listing the same collection members repeatedly.
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226
IM Used
2xxThe server fulfilled a GET using one or more instance manipulations applied to the current resource (delta encoding).
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300
Multiple Choices
3xxThe request has more than one possible response and the client (or user) should choose one of them.
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301
Moved Permanently
3xxThe resource has a new permanent URL given in the Location header. Clients and search engines should update their links.
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302
Found
3xxThe resource is temporarily at a different URL. The original URL should still be used for future requests.
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303
See Other
3xxThe response is at another URL that should be fetched with GET. Often used after a POST to redirect to a result page.
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304
Not Modified
3xxThe cached copy is still fresh, so no body is sent. Returned for conditional requests using If-None-Match or If-Modified-Since.
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307
Temporary Redirect
3xxLike 302, but the request method must not change. A POST stays a POST when following the redirect.
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308
Permanent Redirect
3xxLike 301, but the request method must not change. The permanent way to redirect while preserving POST.
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400
Bad Request
4xxThe server could not understand the request because it was malformed, such as invalid syntax or framing.
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401
Unauthorized
4xxAuthentication is required and has failed or not been provided. Despite the name it means unauthenticated.
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402
Payment Required
4xxReserved for future use. Occasionally used by APIs to signal that payment or a paid plan is needed.
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403
Forbidden
4xxThe server understood the request but refuses to authorize it. Unlike 401, authenticating again will not help.
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404
Not Found
4xxThe server cannot find the requested resource. The most common error, and it does not reveal whether the lack is permanent.
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405
Method Not Allowed
4xxThe HTTP method is not supported for this resource, for example a POST to a read-only endpoint.
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406
Not Acceptable
4xxThe server cannot produce a response matching the Accept headers the client sent.
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407
Proxy Authentication Required
4xxLike 401, but authentication must be done with the proxy before the request can proceed.
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408
Request Timeout
4xxThe server timed out waiting for the request. The client may repeat it on a new connection.
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409
Conflict
4xxThe request conflicts with the current state of the resource, such as an edit based on a stale version.
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410
Gone
4xxThe resource has been permanently removed with no forwarding address. More specific than 404.
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411
Length Required
4xxThe server refuses the request because it lacks a Content-Length header.
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412
Precondition Failed
4xxA condition in the request headers, such as If-Match, was not met by the server.
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413
Content Too Large
4xxThe request body is larger than the server is willing or able to process.
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414
URI Too Long
4xxThe request URI is longer than the server is willing to interpret, often from too much data in the query string.
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415
Unsupported Media Type
4xxThe request body is in a format the server does not support, such as the wrong Content-Type.
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416
Range Not Satisfiable
4xxThe Range header asks for a portion of the resource that does not exist.
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417
Expectation Failed
4xxThe expectation in the Expect request header could not be met by the server.
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418
I'm a teapot
4xxAn April Fools joke from 1998: the server refuses to brew coffee because it is a teapot. Sometimes used as a playful catch-all.
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421
Misdirected Request
4xxThe request was sent to a server that cannot produce a response for the requested authority.
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422
Unprocessable Content
4xxThe request was well formed but has semantic errors, so the server cannot process it. Common for validation failures in APIs.
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423
Locked
4xxA WebDAV code meaning the resource being accessed is locked.
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424
Failed Dependency
4xxA WebDAV code meaning the request failed because a previous request it depended on failed.
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425
Too Early
4xxThe server is unwilling to process a request that might be replayed, to avoid the risk of a replay attack.
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426
Upgrade Required
4xxThe client should switch to a different protocol, given in the Upgrade header, to make this request.
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428
Precondition Required
4xxThe server requires the request to be conditional, to prevent the lost-update problem from concurrent edits.
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429
Too Many Requests
4xxThe client has sent too many requests in a given time (rate limiting). A Retry-After header may say when to try again.
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431
Request Header Fields Too Large
4xxThe server refuses the request because the headers are too large, either individually or in total.
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451
Unavailable For Legal Reasons
4xxThe resource is blocked for legal reasons, such as a government censorship order. The number nods to Fahrenheit 451.
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500
Internal Server Error
5xxA generic catch-all: the server hit an unexpected condition and could not complete the request.
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501
Not Implemented
5xxThe server does not support the functionality required to fulfil the request, for example an unknown method.
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502
Bad Gateway
5xxThe server, acting as a gateway or proxy, got an invalid response from the upstream server.
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503
Service Unavailable
5xxThe server is not ready, usually because it is overloaded or down for maintenance. Often temporary, with a Retry-After.
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504
Gateway Timeout
5xxThe server, acting as a gateway or proxy, did not get a timely response from the upstream server.
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505
HTTP Version Not Supported
5xxThe HTTP version used in the request is not supported by the server.
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506
Variant Also Negotiates
5xxA configuration error in content negotiation: the chosen variant is itself set up to negotiate.
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507
Insufficient Storage
5xxA WebDAV code meaning the server cannot store the representation needed to complete the request.
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508
Loop Detected
5xxA WebDAV code meaning the server detected an infinite loop while processing the request.
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510
Not Extended
5xxFurther extensions to the request are required for the server to fulfil it.
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511
Network Authentication Required
5xxThe client must authenticate to gain network access, typically shown by a captive portal on public Wi-Fi.
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How it works
A quick, searchable reference for HTTP status codes. Every response carries a three-digit code that tells the client how the request went, and they are grouped into five classes by their first digit: 1xx informational, 2xx success, 3xx redirection, 4xx client error, and 5xx server error. Type to search by number or name - "not found" jumps straight to 404 - or use the class chips to browse just the redirects or just the server errors.
Each entry gives the code, its standard name, and a short plain-language explanation of when it is used, with a link to the full specification for the details. It covers the common everyday codes like 200, 301, 404, and 500 alongside the ones that are easy to forget, such as 204 No Content, 422 Unprocessable Content, and 429 Too Many Requests. Everything is static and runs in your browser, so the lookup is instant and works offline once the page has loaded.
Example. Searching 401 shows Unauthorized - the request lacks valid authentication - while 403 Forbidden means you are authenticated but not allowed. Filtering by the 3xx class lists the redirects together, so you can compare 301 Moved Permanently with 302 Found and 307 Temporary Redirect at a glance.
FAQ
What do the HTTP status code classes mean?
The first digit sets the class. 1xx is informational (the request was received and the process continues), 2xx means success, 3xx means a redirect is needed to complete the request, 4xx is a client error such as a bad or unauthorised request, and 5xx is a server error where the server failed to fulfil a valid request. Knowing the class tells you immediately whose side a problem is on.
What is the difference between 401 and 403?
401 Unauthorized means the request has not been authenticated - you are missing or have invalid credentials, so logging in may help. 403 Forbidden means the server knows who you are but you are not allowed to access the resource, so authenticating again will not change the outcome. In short, 401 is about identity and 403 is about permission.
When should I use 301 versus 302?
301 Moved Permanently tells clients and search engines the resource has a new permanent home, so they should update bookmarks and links; it is the right choice for permanent URL changes. 302 Found (and 307) signals a temporary redirect, so the original URL should still be used in future. Picking the right one matters for caching and SEO.
Is anything sent to a server?
No. The reference is a static dataset bundled with the page, and the search and filtering run entirely in your browser. Nothing you type is uploaded, and once the page has loaded the lookup works offline.