HTTP Status Code Lookup

Search every HTTP status code with what it means and when to use it.

Search by code, name or what you are trying to express.

Category

37 of 37 status codes.
Code	Name	Meaning	When to use it
100	Continue	The client should continue with the request body.	Sent in response to an Expect: 100-continue header, so a large body is not uploaded before the server agrees to accept it.
101	Switching Protocols	The server is switching protocols as requested.	This is how a WebSocket connection is established from an HTTP request.
102	Processing	The server has accepted the request but has not completed it.	A WebDAV extension, used to stop a client timing out during a long operation.
103	Early Hints	Preliminary headers sent before the final response.	Lets a browser start preloading critical assets while the server is still generating the page.
200	OK	The request succeeded.	The only status search engines will index content from. Every canonical page should return it.
201	Created	The request succeeded and a new resource was created.	Should include a Location header pointing at the new resource.
202	Accepted	The request was accepted but processing is not complete.	For asynchronous work. Give the client a way to poll for the outcome.
204	No Content	Success, with no body to return.	Correct for a DELETE or a form submission where the client should stay on the current page.
206	Partial Content	Part of the resource is being returned.	Powers resumable downloads and video seeking, in response to a Range header.
301	Moved Permanently	The resource has permanently moved to a new URL.	The right choice for a genuine move. Search engines transfer ranking signals to the new URL and browsers cache it aggressively — which makes it hard to undo.
302	Found	The resource is temporarily at a different URL.	Keeps the original URL indexed. Use for maintenance pages and temporary diversions, never for a permanent move.
303	See Other	Fetch the result at another URL using GET.	The correct redirect after a POST, so a refresh does not resubmit the form.
304	Not Modified	The cached copy is still valid.	Sent in response to a conditional request. Saves bandwidth by returning headers only.
307	Temporary Redirect	Temporary redirect that preserves the request method.	Unlike 302, a POST stays a POST. Prefer it when the method must be preserved.
308	Permanent Redirect	Permanent redirect that preserves the request method.	The method-preserving equivalent of 301.
400	Bad Request	The server could not understand the request.	Use for malformed syntax. If the request is well-formed but semantically wrong, 422 is more precise.
401	Unauthorized	Authentication is required or has failed.	Misleadingly named — it means unauthenticated. Use 403 when the user is known but not permitted.
403	Forbidden	The server understood the request but refuses to authorise it.	The user is authenticated but lacks permission. Repeated 403s can cause search engines to drop a URL.
404	Not Found	The resource does not exist.	Never return 200 with a "not found" page — that creates a soft 404 and wastes crawl budget.
405	Method Not Allowed	The HTTP method is not supported for this resource.	Must include an Allow header listing the methods that are supported.
406	Not Acceptable	No representation matches the Accept headers.	Rare in practice — most servers return their default representation instead.
408	Request Timeout	The client took too long to send the request.	Different from 504, which is a timeout between servers.
409	Conflict	The request conflicts with the current state.	For edit collisions and duplicate-creation attempts. Explain what conflicted.
410	Gone	The resource was deliberately removed and will not return.	Search engines drop 410 URLs faster than 404s. Use it when you have intentionally deleted content.
413	Payload Too Large	The request body exceeds the server limit.	Common on file uploads. Surface the limit in the response body.
415	Unsupported Media Type	The Content-Type is not supported.	Usually a missing or wrong Content-Type header on a JSON request.
418	I'm a teapot	A joke status from a 1998 April Fools RFC.	Not a real status, but implemented by enough servers to have become folklore.
422	Unprocessable Content	The request is well-formed but semantically invalid.	The right status for validation failures — the JSON parsed but a field failed a rule.
429	Too Many Requests	The client has hit a rate limit.	Include a Retry-After header. Clients should back off exponentially rather than retrying immediately.
451	Unavailable For Legal Reasons	Access denied for legal reasons.	Used for court-ordered blocks and geographic restrictions. The number references Fahrenheit 451.
500	Internal Server Error	An unexpected server error occurred.	The generic fallback. Never leak a stack trace in the response — log it server-side instead.
501	Not Implemented	The server does not support the functionality required.	Different from 405, which means the method exists but is not allowed here.
502	Bad Gateway	An upstream server returned an invalid response.	Usually a crashed or unreachable application behind a reverse proxy.
503	Service Unavailable	The server is temporarily unable to handle the request.	The correct status for planned maintenance. Add Retry-After so search engines know to come back rather than deindex.
504	Gateway Timeout	An upstream server did not respond in time.	The proxy gave up waiting for the application. Distinct from 408, which is the client being slow.
507	Insufficient Storage	The server cannot store the representation.	A WebDAV extension, occasionally used for quota exhaustion.
511	Network Authentication Required	The client must authenticate to gain network access.	Used by captive portals on public Wi-Fi.

What does HTTP Status Code Lookup do?

A searchable reference for every HTTP status code, with the specification meaning, practical guidance on when to send it, and the common mistakes. Includes the codes people forget, such as 410, 422 and 429.

How to Use HTTP Status Code Lookup

1
Search for a codeBy number, name or what you are trying to express.
2
Read the meaningThe specification definition plus practical guidance.
3
Check the notesCommon mistakes and SEO implications are called out.

Key Features

Every registered status code from 100 to 511
Search by number, name or description
Practical guidance on when each is appropriate
SEO notes for the redirect and error codes that affect indexing
Grouped by class with plain-English category summaries

Frequently Asked Questions

What is the difference between 301 and 302?

301 is permanent — search engines transfer ranking signals to the new URL and browsers cache it aggressively. 302 is temporary and keeps the original URL indexed. Use 301 for a genuine move, 302 for a temporary diversion such as maintenance.

When should I use 404 versus 410?

404 means not found, possibly temporarily. 410 means gone permanently and never coming back. Search engines drop 410 URLs faster, so use it when you have deliberately removed content.

What does 429 mean?

Too Many Requests — you have hit a rate limit. A well-behaved API includes a Retry-After header telling you how long to wait, and clients should back off exponentially rather than retrying immediately.

Should an API return 200 with an error in the body?

No. Status codes exist so clients, proxies and monitoring can understand outcomes without parsing the body. Use 4xx for client mistakes and 5xx for server failures, and put the detail in the body.