100
ContinueServer received request headers; client should proceed.
HTTP Status Codes
Complete reference for all HTTP status codes — 1xx to 5xx. Search, filter by category, view use cases and RFC references.
1xxInformational4 codesRequest received, continuing process
2xxSuccess10 codesRequest successfully received, understood and accepted
3xxRedirection7 codesFurther action needed to complete the request
4xxClient Error29 codesRequest contains bad syntax or cannot be fulfilled
5xxServer Error11 codesServer failed to fulfil an apparently valid request
Showing 61 of 61 status codes
101
Switching ProtocolsServer is switching protocols as requested by the client.
102
ProcessingServer has received and is processing the request.
103
Early HintsUsed to return response headers before final HTTP message.
200
OKRequest succeeded.
201
CreatedRequest fulfilled and new resource created.
202
AcceptedRequest accepted for processing, but not yet completed.
203
Non-AuthoritativeReturned metadata is from a local or third-party copy.
204
No ContentRequest succeeded but no content to return.
205
Reset ContentServer fulfilled request; client should reset document view.
206
Partial ContentServer is delivering only part of the resource.
207
Multi-StatusResponse contains multiple status codes for multiple operations.
208
Already ReportedMembers already enumerated in previous reply.
226
IM UsedServer fulfilled GET and response is result of instance-manipulations.
300
Multiple ChoicesMultiple options for the resource.
301
Moved PermanentlyResource permanently moved to a new URL.
302
FoundResource temporarily located at a different URI.
303
See OtherResponse to request can be found under another URI using GET.
304
Not ModifiedResource has not changed since last request.
307
Temporary RedirectResource temporarily at different URI; method preserved.
308
Permanent RedirectResource permanently at different URI; method preserved.
400
Bad RequestServer cannot process due to client error.
401
UnauthorizedAuthentication required and failed.
402
Payment RequiredReserved for future use; used for payment-gated content.
403
ForbiddenServer understands request but refuses to authorize it.
404
Not FoundRequested resource could not be found.
405
Method Not AllowedRequest method is not supported for the resource.
406
Not AcceptableServer cannot produce response matching Accept headers.
407
Proxy Auth RequiredClient must authenticate itself with the proxy.
408
Request TimeoutServer timed out waiting for the request.
409
ConflictRequest conflicts with current state of the server.
410
GoneResource is permanently gone; no forwarding address known.
411
Length RequiredRequest must include Content-Length header.
412
Precondition FailedServer does not meet preconditions in request headers.
413
Content Too LargeRequest body is larger than server allows.
414
URI Too LongURI is longer than the server will interpret.
415
Unsupported MediaServer refuses request due to unsupported media format.
416
Range Not SatisfiableRange header cannot be fulfilled.
417
Expectation FailedServer cannot meet requirements of Expect header.
418
I'm a TeapotServer refuses to brew coffee; it is a teapot.
421
Misdirected RequestRequest directed at a server that cannot produce a response.
422
Unprocessable EntityRequest well-formed but unable to process due to semantic errors.
423
LockedResource being accessed is locked.
424
Failed DependencyRequest failed because of failure of a previous request.
425
Too EarlyServer unwilling to risk processing early data.
426
Upgrade RequiredClient must switch to a different protocol.
428
Precondition RequiredRequest must be conditional.
429
Too Many RequestsUser has sent too many requests in a given time (rate limiting).
431
Headers Too LargeRequest headers are too large.
451
Unavailable for LegalResource unavailable for legal reasons.
500
Internal Server ErrorServer encountered an unexpected condition.
501
Not ImplementedServer does not support the functionality required.
502
Bad GatewayServer received invalid response from upstream server.
503
Service UnavailableServer temporarily unable to handle the request.
504
Gateway TimeoutUpstream server failed to send a response in time.
505
HTTP Version Not SupportedHTTP version in request is not supported.
506
Variant Also NegotiatesServer has an internal configuration error.
507
Insufficient StorageServer unable to store representation to complete request.
508
Loop DetectedServer detected infinite loop while processing request.
510
Not ExtendedFurther extensions required for server to fulfil request.
511
Network Auth RequiredClient needs to authenticate to gain network access.
What is HTTP Status Codes?
The HTTP status code reference is a comprehensive developer guide covering every standardised response code defined in the HTTP specification — from informational 1xx codes through successful 2xx responses, redirects in the 3xx range, client errors in the 4xx range, and server errors in the 5xx range. Each entry includes the official code, reason phrase, plain-English explanation, common causes, and practical use cases so developers can quickly understand and act on any status they encounter.
HTTP status codes are the primary way web servers communicate the outcome of a request to clients and intermediaries such as CDNs, proxies, load balancers, and API gateways. Misunderstanding or misusing status codes leads to broken caching, failed redirects, incorrect error handling, and poor API design. For example, returning a 200 OK with an error payload in the body — a common anti-pattern — confuses API clients that rely on status codes to branch logic.
This reference covers both widely used codes like 200, 301, 400, 403, 404, and 500, as well as lesser-known but important codes such as 206 Partial Content for range requests, 429 Too Many Requests for rate limiting, 451 Unavailable For Legal Reasons, and 503 Service Unavailable. Codes are searchable and filterable by category so you can jump straight to what you need without scrolling through the full list.
How to Use HTTP Status Codes
- Search or browse by category
Type a status code number or keyword, or filter by category: 1xx, 2xx, 3xx, 4xx, or 5xx.
- Read the explanation
Click any code to see its official name, plain-English meaning, common causes, and typical use cases.
- Check example scenarios
Each entry includes real-world examples showing when to use the code and what clients should do in response.
- Copy for documentation
Copy any code entry to use in API documentation, error handling guides, or runbook references.
Key Benefits
Complete reference
All standardised HTTP status codes from 100 to 511 in one place — no need to visit multiple spec pages.
Fast search and filter
Find any code instantly by number or keyword, or narrow the list to a single category.
Plain-English explanations
Every code is explained in clear language with real-world examples, not just the official RFC wording.
Developer-focused context
Understand when to use each code in your own API, what clients should do in response, and common pitfalls.
Frequently Asked Questions
A 301 Moved Permanently tells clients and search engines the resource has moved forever — they should update their links and cache the new URL. A 302 Found is a temporary redirect; clients should keep using the original URL.
Use 400 Bad Request for malformed syntax (invalid JSON, missing required fields). Use 422 Unprocessable Entity when the syntax is valid but the content fails business-logic validation.
429 Too Many Requests means the client has sent too many requests in a given time window. Servers include a Retry-After header to tell the client when it can try again.
No. 200 OK indicates success with a response body. 204 No Content indicates success but there is no body to return — commonly used for DELETE requests or actions that do not produce output.