HTTP Status Reference
Quick lookup for HTTP status codes
Continue
The client should continue with its request
Switching Protocols
Server agrees to switch protocols
Processing
Server has received and is processing the request (WebDAV)
Early Hints
Hints for preloading resources before the final response
OK
Request succeeded
Created
Request succeeded and a new resource was created
Accepted
Request accepted but processing not yet completed
Non-Authoritative Information
Response from a third-party copy of the resource
No Content
Request succeeded, no body to return
Reset Content
Ask the client to reset the document view
Partial Content
Partial GET request fulfilled
Multi-Status
Multiple status codes (WebDAV)
Already Reported
Members reported in a previous reply (WebDAV)
IM Used
The server fulfilled a GET request using instance manipulation
Multiple Choices
Multiple options for the resource
Moved Permanently
Resource permanently moved to new URL
Found
Temporary redirect to different URL
See Other
Redirect to another URI using GET
Not Modified
Cached version is still valid
Temporary Redirect
Repeat request with same method to new URL
Permanent Redirect
Permanent redirect; do not change method
Bad Request
Malformed request syntax or invalid parameters
Unauthorized
Authentication required
Payment Required
Reserved for digital payment systems
Forbidden
Server refuses to authorize the request
Not Found
Requested resource could not be found
Method Not Allowed
HTTP method not allowed for the resource
Not Acceptable
Response content type not acceptable to client
Proxy Authentication Required
Client must authenticate with proxy
Request Timeout
Server timed out waiting for request
Conflict
Request conflicts with current state of resource
Gone
Resource permanently deleted
Length Required
Content-Length header required
Precondition Failed
Precondition in request headers failed
Content Too Large
Request body exceeds server limit
URI Too Long
URI is longer than server can process
Unsupported Media Type
Media type not supported by the server
Range Not Satisfiable
Range header cannot be fulfilled
Expectation Failed
Expect header cannot be met
I'm a Teapot
The server refuses to brew coffee (April Fools RFC 2324)
Misdirected Request
Request directed at a server unable to produce a response
Unprocessable Content
Request well-formed but semantic errors
Locked
Resource being accessed is locked (WebDAV)
Failed Dependency
Method failed due to previous dependent request (WebDAV)
Too Early
Server unwilling to risk replaying early data
Upgrade Required
Client must upgrade to use the service
Precondition Required
Server requires conditional request
Too Many Requests
Client exceeded rate limit
Request Header Fields Too Large
Header fields too large
Unavailable For Legal Reasons
Resource unavailable due to legal reasons
Internal Server Error
Generic server error
Not Implemented
Server does not support the functionality
Bad Gateway
Invalid response from upstream server
Service Unavailable
Server temporarily unavailable or overloaded
Gateway Timeout
Upstream server timed out
HTTP Version Not Supported
HTTP version used in request not supported
Variant Also Negotiates
Content negotiation circular reference
Insufficient Storage
Server unable to store representation (WebDAV)
Loop Detected
Infinite loop detected (WebDAV)
Not Extended
Further extensions required to fulfil the request
Network Authentication Required
Client must authenticate for network access
About the HTTP Status Code Reference
This HTTP status codes reference lists every code from 100 to 599 with its meaning and the practical difference between similar ones — which matters because caches, browsers and crawlers all behave differently per code.
HTTP status codes are grouped by first digit: 2xx succeeded, 3xx redirects, 4xx the client got it wrong, 5xx the server did. That much is widely known; the distinctions within each group are what get looked up.
The redirect pair matters most. A 301 is permanent and is cached aggressively by browsers and treated by search engines as a signal to transfer ranking to the new URL; a 302 is temporary and transfers nothing. Using 301 during a migration you later reverse is genuinely painful, because browsers keep following the cached redirect.
On the error side, 404 says the resource is not there while 410 says it was deliberately removed, and crawlers drop a 410 faster. A 503 tells a crawler to come back rather than to drop the page, which is why it is the correct response during maintenance. To check what a live URL actually returns, use the HTTP status checker.
How to use the HTTP Status Code Reference
- Find the code. Browse by class or search for the specific number.
- Read the meaning. See what the code asserts and when it applies.
- Check the handling. Note how browsers, caches and crawlers treat it.
- Pick the right one. Choose the code that matches your intent, not just the class.
HTTP Status Code Reference features
- Every status code from 100 to 599
- Grouped by class: informational, success, redirection, client error, server error
- The practical difference between codes that look similar
- Notes on how caches, browsers and crawlers treat each one
- A static reference — nothing is sent anywhere
Frequently asked questions
What do the code classes mean?
1xx is informational, 2xx succeeded, 3xx means look elsewhere, 4xx blames the request and 5xx blames the server. That first digit is the part clients and crawlers act on.
301 or 302?
301 is permanent and transfers ranking signals to the new URL; 302 is temporary and does not. Use 301 when a page has genuinely moved for good — and note that 301s are cached hard by browsers, so a mistaken one is painful to undo.
404 or 410?
404 means not found, which crawlers keep rechecking for a long time. 410 means intentionally gone, which gets the URL dropped faster. Use 410 when you have deliberately removed something permanently.
Which code should a failed form validation return?
400 for a malformed request, or 422 when the request is well-formed but the values are unacceptable. Returning 200 with an error message in the body is common and wrong — it breaks caching, monitoring and any client that checks the status.
What does 429 mean for an API client?
Too many requests: you have been rate limited. Look for a Retry-After header and honour it, backing off exponentially rather than retrying immediately — which is how a rate limit turns into a ban.