HTTP Status Code Lookup

1xx Informational

The request headers were received and the client should continue sending the request body.

Common use: Interim reply to an Expect: 100-continue header before a large upload.

Reference: RFC 9110 §15.2.1

1xx Informational

The server agrees to switch to the protocol named in the client's Upgrade header.

Common use: Handshake response when upgrading an HTTP connection to WebSocket.

Reference: RFC 9110 §15.2.2

1xx Informational · Historical / deprecated

The server has accepted the request but has not yet completed it; defined for WebDAV.

Common use: Rarely used interim reply to keep a slow WebDAV client from timing out.

Removed from the later WebDAV spec (RFC 4918); still listed by IANA.

Reference: RFC 2518

1xx Informational

Sends preliminary headers, typically Link, so the client can start preloading resources.

Common use: Performance hint that lets browsers preconnect or preload before the final response.

Reference: RFC 8297

1xx Informational · Temporary registration

Interim reply telling the client that the server supports resuming an interrupted upload of this request.

Common use: Signalled early in a large PATCH/POST upload so the client can resume after a network drop instead of restarting.

Temporary IANA registration (first registered 2024-11-13, extended 2025-09-15), currently listed as expiring 2026-11-13; this Tooliba snapshot was reviewed on 2026-08-31. What happens to the code after expiry is not guaranteed.

Reference: draft-ietf-httpbis-resumable-upload-05

2xx Successful

The request succeeded; the meaning of the response body depends on the method used.

Common use: Standard success reply for GET, and for POST/PUT that return a representation.

Reference: RFC 9110 §15.3.1

2xx Successful

The request succeeded and one or more new resources were created as a result.

Common use: Reply to a POST or PUT that creates a record; often includes a Location header.

Reference: RFC 9110 §15.3.2

2xx Successful

The request was accepted for processing, but processing has not completed and may still fail.

Common use: Acknowledges an asynchronous job that will run in the background.

Reference: RFC 9110 §15.3.3

2xx Successful

The response is a modified version of the origin's answer, altered by a transforming proxy.

Common use: Signals that an intermediary changed the payload or headers.

Reference: RFC 9110 §15.3.4

2xx Successful

The request succeeded and there is deliberately no response body to send.

Common use: Reply to a successful DELETE or an update that returns nothing.

A 204 response must not carry a message body.

Reference: RFC 9110 §15.3.5

2xx Successful

The request succeeded and the client should reset the document view that sent the request.

Common use: Tells a form-based UI to clear its fields after a submission.

Reference: RFC 9110 §15.3.6

2xx Successful

The server is delivering only part of the resource, as requested by a Range header.

Common use: Resumable downloads and media seeking with byte-range requests.

Reference: RFC 9110 §15.3.7

2xx Successful

Conveys the status of several independent operations in one XML body; defined for WebDAV.

Common use: WebDAV batch operations such as a multi-resource PROPFIND.

Reference: RFC 4918

2xx Successful

Used inside a Multi-Status body to avoid listing the same collection members repeatedly.

Common use: WebDAV bindings where a resource would otherwise be enumerated more than once.

Reference: RFC 5842

2xx Successful

The GET response is the result of applying one or more instance-manipulations to the resource.

Common use: Delta encoding, where only changes since a prior version are returned.

Reference: RFC 3229

3xx Redirection

The target has more than one representation and the client or user may pick one.

Common use: Rarely used; agent-driven content negotiation with a list of options.

Reference: RFC 9110 §15.4.1

3xx Redirection

The resource has a new permanent URL given in Location; clients should update their links.

Common use: Permanent site or page moves; search engines transfer ranking to the new URL.

For historical reasons clients may change a POST to GET when following it; use 308 to preserve the method.

Reference: RFC 9110 §15.4.2

3xx Redirection

The resource is temporarily at a different URL given in Location; keep using the original URL.

Common use: Temporary redirects; historically many clients switch POST to GET when following it.

Use 307 to guarantee the request method is preserved on the redirect.

Reference: RFC 9110 §15.4.3

3xx Redirection

The response is at another URL that should be retrieved with GET, regardless of the original method.

Common use: Post/Redirect/Get pattern: send the browser to a result page after a form POST.

Reference: RFC 9110 §15.4.4

3xx Redirection

The cached copy is still fresh for a conditional request; no body is sent.

Common use: Response to If-None-Match or If-Modified-Since so the client reuses its cache.

It is a cache validation result, not a redirect, and carries no message body.

Reference: RFC 9110 §15.4.5

3xx Redirection · Historical / deprecated

The resource must be accessed through the proxy given in Location.

Common use: Deprecated for security reasons; modern clients must not honour it.

Reference: RFC 9110 §15.4.6

3xx Redirection · Historical / deprecated

Reserved. It was defined in a previous HTTP draft and is no longer used.

Common use: Not used by servers; kept reserved in the registry.

Reference: RFC 9110 §15.4.7

3xx Redirection

Like 302, but the client must repeat the request to the new URL with the same method and body.

Common use: Temporary redirects where a POST must stay a POST.

Reference: RFC 9110 §15.4.8

3xx Redirection

Like 301, but the client must not change the request method when following it.

Common use: Permanent redirects for APIs and forms where the method and body must be preserved.

Reference: RFC 9110 §15.4.9

4xx Client Error

The server cannot or will not process the request because it is malformed.

Common use: Invalid syntax, bad framing, or a payload the server cannot parse at all.

Reference: RFC 9110 §15.5.1

4xx Client Error

Authentication is required or has failed; the response includes a WWW-Authenticate challenge.

Common use: Missing, expired, or invalid credentials on a protected endpoint.

Despite the name, it means "unauthenticated". Use 403 when the identity is known but not allowed.

Reference: RFC 9110 §15.5.2

4xx Client Error

Reserved for future use; occasionally used by APIs to signal a billing or quota problem.

Common use: Non-standard use by some paid APIs when a subscription is inactive.

Reference: RFC 9110 §15.5.3

4xx Client Error

The server understood the request but refuses to authorize it; re-authenticating will not help.

Common use: Known identity without permission, IP blocks, or disabled features.

It is not "authentication failed" — that is 401.

Reference: RFC 9110 §15.5.4

4xx Client Error

The server has no current representation for the target and does not say whether it ever existed.

Common use: Unknown URL, deleted page, or a resource the server chooses to hide.

Reference: RFC 9110 §15.5.5

4xx Client Error

The HTTP method is not supported for this resource; the Allow header lists the accepted methods.

Common use: Sending POST to a read-only endpoint, or DELETE where it is not permitted.

Reference: RFC 9110 §15.5.6

4xx Client Error

The server cannot produce a response matching the request's Accept headers.

Common use: Proactive content negotiation fails, e.g. no acceptable media type or language.

Reference: RFC 9110 §15.5.7

4xx Client Error

Like 401, but the client must authenticate with the proxy using Proxy-Authenticate.

Common use: Corporate or ISP proxies that require sign-in before forwarding traffic.

Reference: RFC 9110 §15.5.8

4xx Client Error

The server timed out waiting for the client to finish sending the request.

Common use: Idle or very slow clients; the connection may be closed afterwards.

Reference: RFC 9110 §15.5.9

4xx Client Error

The request conflicts with the current state of the target resource.

Common use: Concurrent edits, duplicate creation, or a version mismatch on update.

Reference: RFC 9110 §15.5.10

4xx Client Error

The resource is permanently unavailable and the server expects no forwarding address.

Common use: Intentionally removed content; a stronger, permanent signal than 404.

Unlike 404, it asserts the removal is permanent and links should be dropped.

Reference: RFC 9110 §15.5.11

4xx Client Error

The server refuses the request because it lacks a Content-Length header.

Common use: Endpoints that will not accept a body of unknown length.

Reference: RFC 9110 §15.5.12

4xx Client Error

One or more conditions from the request's conditional headers evaluated to false.

Common use: If-Match or If-Unmodified-Since guards that prevent a lost update.

Reference: RFC 9110 §15.5.13

4xx Client Error

The request body is larger than the server is willing or able to process.

Common use: Upload size limits; a Retry-After header may accompany a temporary refusal.

Previously called "Payload Too Large" (and "Request Entity Too Large").

Reference: RFC 9110 §15.5.14

4xx Client Error

The request target is longer than the server is willing to interpret.

Common use: Excessive query strings, often from a GET that should have been a POST.

Reference: RFC 9110 §15.5.15

4xx Client Error

The payload's format is not supported by the target resource for this method.

Common use: Sending XML to a JSON-only API, or an unexpected Content-Type or encoding.

Reference: RFC 9110 §15.5.16

4xx Client Error

None of the ranges in the request's Range header overlap the current resource.

Common use: A resume request whose byte offset is past the end of the file.

Reference: RFC 9110 §15.5.17

4xx Client Error

The expectation in the request's Expect header could not be met by the server.

Common use: A server or proxy that does not support Expect: 100-continue.

Reference: RFC 9110 §15.5.18

4xx Client Error · Historical / deprecated

Reserved. It originates from an April Fools' joke RFC and must not be implemented.

Common use: Sometimes returned playfully by servers; not a real error condition.

Reference: RFC 9110 §15.5.19

4xx Client Error

The request reached a server that is not able or configured to produce a response for it.

Common use: HTTP/2 connection reuse where the authority does not match this server.

Reference: RFC 9110 §15.5.20

4xx Client Error

The syntax is valid but the server cannot process the contained instructions.

Common use: Semantic validation failures in an otherwise well-formed JSON or XML body.

Formerly "Unprocessable Entity" and defined only for WebDAV; RFC 9110 makes it general.

Reference: RFC 9110 §15.5.21

4xx Client Error

The target resource is locked; defined for WebDAV.

Common use: WebDAV write locks held by another user or client.

Reference: RFC 4918

4xx Client Error

The request failed because it depended on another request that did not succeed; WebDAV.

Common use: A step in a WebDAV batch cannot run because an earlier step failed.

Reference: RFC 4918

4xx Client Error

The server is unwilling to process a request that might be replayed from TLS early data.

Common use: TLS 1.3 0-RTT protection against replay attacks.

Reference: RFC 8470

4xx Client Error

The server refuses the request on the current protocol but may accept it after an upgrade.

Common use: Requiring TLS or a newer HTTP version via the Upgrade header.

Reference: RFC 9110 §15.5.22

4xx Client Error

The server requires the request to be conditional to avoid a lost update.

Common use: APIs that demand an If-Match header on unsafe methods.

Reference: RFC 6585

4xx Client Error

The client has sent too many requests in a given time and is being rate limited.

Common use: API rate limiting; a Retry-After header may indicate when to try again.

A Retry-After header is allowed but not guaranteed.

Reference: RFC 6585

4xx Client Error

The server refuses the request because a header field, or all of them together, is too large.

Common use: Oversized cookies or a very long Referer or Authorization header.

Reference: RFC 6585

4xx Client Error

The resource is denied as a result of a legal demand, such as a court order.

Common use: Government-ordered censorship or geo-blocking of specific content.

Reference: RFC 7725

5xx Server Error

The server hit an unexpected condition that stopped it from fulfilling the request.

Common use: Generic catch-all for unhandled exceptions and server-side bugs.

Reference: RFC 9110 §15.6.1

5xx Server Error

The server does not support the functionality required to fulfil the request.

Common use: An unknown request method or a feature the server has never implemented.

Reference: RFC 9110 §15.6.2

5xx Server Error

A server acting as a gateway or proxy got an invalid response from the upstream server.

Common use: A reverse proxy whose backend is down, crashed, or returned garbage.

Reference: RFC 9110 §15.6.3

5xx Server Error

The server is temporarily unable to handle the request, often due to overload or maintenance.

Common use: Planned downtime or traffic spikes; a Retry-After header may be included.

Reference: RFC 9110 §15.6.4

5xx Server Error

A gateway or proxy did not get a timely response from the upstream server.

Common use: A backend that is too slow or unreachable behind a reverse proxy.

Reference: RFC 9110 §15.6.5

5xx Server Error

The server does not support the major HTTP version used in the request.

Common use: A client speaking a protocol version the server refuses.

Reference: RFC 9110 §15.6.6

5xx Server Error

A content-negotiation configuration error makes the chosen variant negotiate again in a loop.

Common use: Misconfigured transparent content negotiation on the server.

Reference: RFC 2295

5xx Server Error

The server cannot store the representation needed to complete the request; defined for WebDAV.

Common use: A WebDAV PUT or COPY that would exceed the account's disk quota.

Reference: RFC 4918

5xx Server Error

The server ended an operation because it encountered an infinite loop while processing it; WebDAV.

Common use: Cyclic bindings during a WebDAV depth request.

Reference: RFC 5842

5xx Server Error · Historical / deprecated

Further extensions to the request are required for the server to fulfil it.

Common use: From the experimental HTTP extension framework; effectively unused.

Reference: RFC 2774

5xx Server Error

The client must authenticate to gain network access, typically at a captive portal.

Common use: Wi-Fi captive portals injected by an intermediary, not by the origin server.

Reference: RFC 6585