Developer tools

HTTP Status Codes for Webhooks & Health Checks

Look up any HTTP status code and see what it means in practice: should a webhook sender retry, and should an uptime check call the endpoint healthy?

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Class

Only codes worth retrying

Code	Meaning	Webhook sender: retry?	Health check
100	Continue The server received the request headers, so the client can send the body.	– Not a final response	–
101	Switching Protocols The server is switching protocols, for example to WebSocket.	– Not a final response	–
102	Processing WebDAV: the server is still working on the request.	– Not a final response	–
103	Early Hints Preliminary headers, such as preload links, sent before the final response.	– Not a final response	–
200	OK The request succeeded.	No Delivered	Healthy
201	Created The request succeeded and created a new resource.	No Delivered	Healthy
202	Accepted The request was accepted, but processing hasn’t finished.	No Delivered	Healthy
203	Non-Authoritative Information The response was modified by a proxy.	No Delivered	Healthy
204	No Content The request succeeded and there is no body to return.	No Delivered	Healthy
205	Reset Content The request succeeded; the client should reset the form or view.	No Delivered	Healthy
206	Partial Content The server is returning part of the resource, as asked for with a Range header.	No Delivered	Healthy
207	Multi-Status WebDAV: the body contains statuses for several operations.	No Delivered	Healthy
208	Already Reported WebDAV: these members were already listed earlier in the response.	No Delivered	Healthy
226	IM Used The server applied instance manipulations, such as delta encoding.	No Delivered	Healthy
300	Multiple Choices Several representations of the resource are available.	No Most senders count a redirect as a failure, so update the URL	Check URL
301	Moved Permanently The resource has a new permanent URL.	No Most senders count a redirect as a failure, so update the URL	Check URL
302	Found The resource is temporarily at another URL.	No Most senders count a redirect as a failure, so update the URL	Check URL
303	See Other Fetch the result from another URL with GET.	No Most senders count a redirect as a failure, so update the URL	Check URL
304	Not Modified The cached copy is still valid.	No Most senders count a redirect as a failure, so update the URL	Check URL
307	Temporary Redirect Temporarily at another URL; repeat the request with the same method and body.	No Most senders count a redirect as a failure, so update the URL	Check URL
308	Permanent Redirect Permanently at another URL; repeat the request with the same method and body.	No Most senders count a redirect as a failure, so update the URL	Check URL
400	Bad Request The server can’t process the request because it is malformed.	No Permanent: fix the request or the endpoint	Unhealthy
401	Unauthorized The request has no valid credentials.	No Permanent: fix the request or the endpoint	Unhealthy
402	Payment Required Reserved; some APIs use it for billing problems.	No Permanent: fix the request or the endpoint	Unhealthy
403	Forbidden The server understood the request but won’t allow it.	No Permanent: fix the request or the endpoint	Unhealthy
404	Not Found Nothing exists at this URL.	No Permanent: fix the request or the endpoint	Unhealthy
405	Method Not Allowed The URL doesn’t accept this HTTP method.	No Permanent: fix the request or the endpoint	Unhealthy
406	Not Acceptable No representation matches the request’s Accept headers.	No Permanent: fix the request or the endpoint	Unhealthy
407	Proxy Authentication Required A proxy between the client and server needs credentials.	No Permanent: fix the request or the endpoint	Unhealthy
408	Request Timeout The server gave up waiting for the client to send the request.	Retry Temporary: retry with backoff	Unhealthy
409	Conflict The request conflicts with the current state of the resource.	No Permanent: fix the request or the endpoint	Unhealthy
410	Gone The resource was permanently removed.	No Permanent: fix the request or the endpoint	Unhealthy
411	Length Required The server requires a Content-Length header.	No Permanent: fix the request or the endpoint	Unhealthy
412	Precondition Failed A condition in the request headers wasn’t met.	No Permanent: fix the request or the endpoint	Unhealthy
413	Content Too Large The request body is larger than the server accepts.	No Permanent: fix the request or the endpoint	Unhealthy
414	URI Too Long The URL is longer than the server accepts.	No Permanent: fix the request or the endpoint	Unhealthy
415	Unsupported Media Type The server doesn’t accept the request’s Content-Type.	No Permanent: fix the request or the endpoint	Unhealthy
416	Range Not Satisfiable The requested byte range isn’t available.	No Permanent: fix the request or the endpoint	Unhealthy
417	Expectation Failed The server can’t meet the Expect header.	No Permanent: fix the request or the endpoint	Unhealthy
418	I’m a teapot An April Fools’ joke from RFC 2324, sometimes used to turn away bots.	No Permanent: fix the request or the endpoint	Unhealthy
421	Misdirected Request The request reached a server that can’t answer for this hostname.	No Permanent: fix the request or the endpoint	Unhealthy
422	Unprocessable Content The request is well-formed but fails validation.	No Permanent: fix the request or the endpoint	Unhealthy
423	Locked WebDAV: the resource is locked.	No Permanent: fix the request or the endpoint	Unhealthy
424	Failed Dependency WebDAV: the request depended on another request that failed.	No Permanent: fix the request or the endpoint	Unhealthy
425	Too Early The server won’t process a request that might be replayed.	Retry Temporary: retry with backoff	Unhealthy
426	Upgrade Required The client must switch to a different protocol.	No Permanent: fix the request or the endpoint	Unhealthy
428	Precondition Required The server requires a conditional request.	No Permanent: fix the request or the endpoint	Unhealthy
429	Too Many Requests The client is being rate limited. Check the Retry-After header.	Retry Temporary: back off and honour Retry-After	Degraded
431	Request Header Fields Too Large The request headers are too large.	No Permanent: fix the request or the endpoint	Unhealthy
451	Unavailable For Legal Reasons Access is blocked for legal reasons.	No Permanent: fix the request or the endpoint	Unhealthy
500	Internal Server Error The server hit an unexpected error.	Retry Temporary: retry with backoff	Unhealthy
501	Not Implemented The server doesn’t support what the request needs.	No Permanent: fix the request or the endpoint	Unhealthy
502	Bad Gateway A proxy got an invalid response from the server behind it.	Retry Temporary: retry with backoff	Unhealthy
503	Service Unavailable The server is overloaded or down for maintenance.	Retry Temporary: back off and honour Retry-After	Unhealthy
504	Gateway Timeout A proxy gave up waiting for the server behind it.	Retry Temporary: retry with backoff	Unhealthy
505	HTTP Version Not Supported The server doesn’t support the request’s HTTP version.	No Permanent: fix the request or the endpoint	Unhealthy
506	Variant Also Negotiates The server’s content negotiation is misconfigured.	No Permanent: fix the request or the endpoint	Unhealthy
507	Insufficient Storage WebDAV: the server can’t store what the request needs.	Retry Temporary: retry with backoff	Unhealthy
508	Loop Detected WebDAV: the server found an infinite loop.	No Permanent: fix the request or the endpoint	Unhealthy
510	Not Extended The server needs further extensions to fulfil the request.	No Permanent: fix the request or the endpoint	Unhealthy
511	Network Authentication Required The client must sign in to the network, such as a captive portal.	No Permanent: fix the request or the endpoint	Unhealthy

How to use the HTTP Status Code Lookup

Search by number, such as 429, or by name, such as “gateway”.
Filter to a class, such as 4xx client errors.
Read the retry and health-check advice.
Use it to decide how your sender, receiver or monitor should react.

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Frequently asked questions

401 Unauthorized means the request has no valid credentials: sign in or send a token. 403 Forbidden means the server knows who you are but won’t allow the action.

502 Bad Gateway means a proxy got an invalid response from the server behind it. 503 Service Unavailable means the server is overloaded or down for maintenance. 504 Gateway Timeout means a proxy gave up waiting for the server behind it. All three are usually temporary and worth retrying.

Either works; senders treat any 2xx response as success. Return it quickly, after storing or queueing the event.

Most webhook senders don’t follow redirects and treat them as failed deliveries. Configure the final URL, including the correct scheme and trailing slash.

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