1xx · Standard HTTP status
100 Continue
Server received headers; client may send the body.
Typical use: Use for request-body negotiation.
Caveat: Intermediaries may handle it invisibly.
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HTTP reference
HTTP Status Code Lookup
Search common standardized HTTP response codes by number, phrase, category, meaning and typical use.
1xx · Standard HTTP status
101 Switching Protocols
Server is changing protocols.
Typical use: WebSocket upgrade handshakes.
Caveat: Requires an Upgrade request.
2xx · Standard HTTP status
200 OK
Request succeeded.
Typical use: Successful reads or updates.
Caveat: A more specific 2xx may communicate better.
2xx · Standard HTTP status
201 Created
A new resource was created.
Typical use: Successful POST creation.
Caveat: Usually include a Location header.
2xx · Standard HTTP status
202 Accepted
Request was accepted for later processing.
Typical use: Asynchronous jobs.
Caveat: Does not mean processing succeeded.
2xx · Standard HTTP status
204 No Content
Request succeeded without a response body.
Typical use: Successful delete or update.
Caveat: Must not include message content.
2xx · Standard HTTP status
206 Partial Content
Response contains a requested byte range.
Typical use: Downloads and media seeking.
Caveat: Requires valid range semantics.
3xx · Standard HTTP status
301 Moved Permanently
Resource has a permanent new URL.
Typical use: Permanent redirects.
Caveat: Clients may change POST to GET historically.
3xx · Standard HTTP status
302 Found
Resource is temporarily elsewhere.
Typical use: Temporary redirects.
Caveat: Method handling varies; 307 is explicit.
3xx · Standard HTTP status
304 Not Modified
Cached representation is still valid.
Typical use: Conditional GET or HEAD.
Caveat: It is not a normal 3xx navigation redirect.
3xx · Standard HTTP status
307 Temporary Redirect
Temporary redirect preserving method and body.
Typical use: Temporary API redirects.
Caveat: Original method is repeated at destination.
3xx · Standard HTTP status
308 Permanent Redirect
Permanent redirect preserving method and body.
Typical use: Permanent API redirects.
Caveat: Original method is repeated at destination.
4xx · Standard HTTP status
400 Bad Request
Request syntax or framing is invalid.
Typical use: Malformed input.
Caveat: Use validation details without leaking internals.
4xx · Standard HTTP status
401 Unauthorized
Authentication is required or failed.
Typical use: Missing or invalid credentials.
Caveat: HTTP name is historical; it means unauthenticated.
4xx · Standard HTTP status
403 Forbidden
Server understood but refuses the request.
Typical use: Authenticated user lacks permission.
Caveat: Do not use when authentication is merely missing.
4xx · Standard HTTP status
404 Not Found
Target resource was not found.
Typical use: Unknown route or hidden resource.
Caveat: May intentionally conceal a forbidden resource.
4xx · Standard HTTP status
405 Method Not Allowed
Method is not supported for this target.
Typical use: POST sent to a read-only endpoint.
Caveat: Include the Allow header.
4xx · Standard HTTP status
408 Request Timeout
Server timed out waiting for the request.
Typical use: Slow or idle client request.
Caveat: Distinct from gateway timeout 504.
4xx · Standard HTTP status
409 Conflict
Request conflicts with current resource state.
Typical use: Version or uniqueness conflicts.
Caveat: Often paired with actionable conflict details.
4xx · Standard HTTP status
410 Gone
Resource was intentionally removed permanently.
Typical use: Retired content.
Caveat: Stronger permanence signal than 404.
4xx · Standard HTTP status
413 Content Too Large
Request content exceeds a limit.
Typical use: Upload size limits.
Caveat: Previously called Payload Too Large.
4xx · Standard HTTP status
415 Unsupported Media Type
Request format is unsupported.
Typical use: Wrong Content-Type.
Caveat: Explain accepted media types where useful.
4xx · Standard HTTP status
422 Unprocessable Content
Syntax is valid but instructions cannot be processed.
Typical use: Semantic validation failures.
Caveat: Current standardized phrase is Unprocessable Content.
4xx · Standard HTTP status
429 Too Many Requests
Client exceeded a rate limit.
Typical use: API throttling.
Caveat: Retry-After may communicate timing.
5xx · Standard HTTP status
500 Internal Server Error
Unexpected server failure.
Typical use: Unhandled server errors.
Caveat: Avoid exposing sensitive internals.
5xx · Standard HTTP status
501 Not Implemented
Server lacks functionality for the request.
Typical use: Unsupported method capability.
Caveat: Not the same as a temporarily disabled feature.
5xx · Standard HTTP status
502 Bad Gateway
Gateway received an invalid upstream response.
Typical use: Proxy or upstream failure.
Caveat: Investigate the upstream service.
5xx · Standard HTTP status
503 Service Unavailable
Service is temporarily unable to respond.
Typical use: Maintenance or overload.
Caveat: Retry-After may be appropriate.
5xx · Standard HTTP status
504 Gateway Timeout
Gateway did not receive an upstream response in time.
Typical use: Upstream timeout.
Caveat: Distinct from client request timeout 408.
About HTTP Status Code Lookup
Use a focused reference for common standardized informational, success, redirect, client-error and server-error responses.
How to use this tool
- 1Search by number, phrase or meaning.
- 2Optionally filter by 1xx through 5xx.
- 3Read typical use and caveat.
- 4Confirm protocol details when implementing edge cases.
Understanding the result
The first digit identifies the response class.
A status code communicates response semantics, not necessarily the complete application error.
Important limitations
- This is a curated common-code reference rather than every registered or vendor-specific code.
- Implementation details should be checked against current HTTP specifications.
Explore this topic
Frequently asked questions
What is the difference between 401 and 403?
401 generally means authentication is missing or failed; 403 means the request is understood but refused.
What is 422 called?
The current standardized phrase is Unprocessable Content.
Are nonstandard codes included?
No. Every displayed entry is labeled as standardized.
Related tools
Selected from curated relationships first, then the same subtopic and category.