HTTP Status Code Reference
Search HTTP response codes by number, name, class, or keyword. Switch between card and table views, show common codes only, and open any response code for an explanation, example, and standards note.
Find an HTTP response code
| Code | Name | Class | Status | Summary |
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How HTTP Status Codes Work
Every HTTP response contains a numeric status code that summarizes what happened to the request. The first digit defines the broad response class: 1xx is informational, 2xx indicates success, 3xx indicates redirection, 4xx represents a client-side request problem, and 5xx represents a server-side failure while handling an apparently valid request.
This reference focuses on codes in the IANA HTTP Status Code Registry and preserves important registry distinctions such as temporary, obsolete, WebDAV, deprecated, and unused entries. A server can technically emit unregistered or vendor-specific response codes, but those should not be assumed to have interoperable meaning outside the implementation that defines them.
Common HTTP Status Code Patterns
200 vs. 201 vs. 204
200 OK is the general success response. 201 Created is more specific when the request creates a new resource. 204 No Content indicates success when no response body needs to be sent.
301 vs. 302 vs. 307 vs. 308
301 and 308 are permanent redirects, while 302 and 307 are temporary. The important method-preservation distinction is that 307 and 308 explicitly preserve the original request method and body when the redirect is followed.
401 vs. 403
401 Unauthorized is primarily an authentication response: credentials are missing, invalid, or otherwise insufficient to establish authentication. 403 Forbidden means the server understood the request but refuses to authorize it.
404 vs. 410
404 Not Found says the server cannot find a matching resource or chooses not to disclose one. 410 Gone is more explicit: the resource is known to have been intentionally removed and is expected to remain unavailable.
502 vs. 503 vs. 504
502 Bad Gateway means a gateway received an invalid upstream response. 503 Service Unavailable is a temporary service-capacity or maintenance condition. 504 Gateway Timeout means a gateway waited too long for an upstream response.
Practical Uses
API development
Choose response codes that accurately describe the outcome of an operation so API clients can distinguish success, validation problems, authentication failures, conflicts, throttling, and server failures without parsing human-readable text.
Debugging
Browser developer tools, HAR files, command-line clients, reverse proxies, and application logs commonly expose HTTP status codes. Looking up the code is often the fastest way to decide whether to investigate client input, authentication, redirects, cache behavior, application logic, or upstream infrastructure.
Redirect and SEO work
Permanent and temporary redirect codes communicate different intent. Method-preserving redirects also matter for APIs and form submissions, where changing POST or PUT into GET can change application behavior.
Rate limiting and reliability
Codes such as 429, 502, 503, and 504 are important in resilient clients. Applications often combine them with retry logic, backoff, monitoring, and headers such as Retry-After where appropriate.
IANA HTTP Status Code Registry · MDN HTTP response status codes
HTTP Status Code FAQ
What does the first digit of an HTTP status code mean?
It identifies the response class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, or 5xx server error.
What is the difference between 401 and 403?
401 indicates that authentication is required or invalid. 403 means the server understood the request but refuses to authorize it.
What is the difference between 301 and 308?
Both indicate permanent redirection, but 308 explicitly preserves the original request method and body when the redirect is followed.
What does 429 Too Many Requests mean?
The client has exceeded a request-rate limit. The response may include Retry-After guidance for a later attempt.
Is 418 I'm a Teapot a standard HTTP status code?
The number is historically famous for the teapot joke, but the current core HTTP registry lists 418 as unused. It should not be treated as a portable application protocol signal.
What is HTTP 104?
104 Upload Resumption Supported is a temporary IANA registration associated with the current resumable-upload draft. As of September 2026, the registry lists the temporary registration as expiring November 13, 2026 unless it is extended or superseded.