Search HTTP response codes and see plain-English meanings with common causes.
100
1xx Informational
Request headers received; continue sending body.
Common cause: Large upload request accepted by server.
101
1xx Informational
Server is switching protocols (e.g. WebSocket).
Common cause: Upgrade header in handshake flow.
200
2xx Success
Request succeeded and response includes requested data.
Common cause: Normal successful API/page request.
201
2xx Success
Resource created successfully.
Common cause: POST endpoint creating a record.
204
2xx Success
Request succeeded but response body is empty.
Common cause: DELETE or update endpoint with no response payload.
301
3xx Redirection
Resource has a permanent new URL.
Common cause: Domain or URL migration with redirect.
302
3xx Redirection
Resource temporarily available at another URL.
Common cause: Temporary redirect after auth or flow checks.
304
3xx Redirection
Cached version is still valid; no body returned.
Common cause: Conditional request with ETag/If-Modified-Since.
400
4xx Client Error
Request is malformed or invalid.
Common cause: Invalid JSON, missing required fields, wrong params.
401
4xx Client Error
Authentication required or token invalid.
Common cause: Missing/expired auth token.
403
4xx Client Error
Authenticated but not allowed to access resource.
Common cause: Role/permission check failed.
404
4xx Client Error
Requested resource does not exist.
Common cause: Wrong URL, deleted resource, or bad route.
405
4xx Client Error
HTTP method is not supported on this route.
Common cause: Sending POST to a GET-only endpoint.
409
4xx Client Error
Request conflicts with current resource state.
Common cause: Duplicate unique value or edit race conflict.
410
4xx Client Error
Resource existed before but is permanently removed.
Common cause: Old endpoint intentionally retired.
413
4xx Client Error
Request body exceeds allowed size.
Common cause: Upload exceeds server/body parser limits.
415
4xx Client Error
Server does not support request content type.
Common cause: Wrong Content-Type header (e.g. text/plain vs application/json).
422
4xx Client Error
Request syntax is valid but semantic validation fails.
Common cause: Business validation error, invalid field format, failed schema constraints.
429
4xx Client Error
Rate limit exceeded.
Common cause: Burst traffic or repeated API calls.
500
5xx Server Error
Unexpected server-side failure occurred.
Common cause: Unhandled exception in application code.
502
5xx Server Error
Proxy/gateway got invalid upstream response.
Common cause: Upstream service unavailable or returned malformed response.
503
5xx Server Error
Server temporarily unavailable.
Common cause: Maintenance window, overload, or dependency outage.
504
5xx Server Error
Gateway timed out waiting for upstream.
Common cause: Slow downstream service or network timeout.
Yes, HTTP Status Code Reference is completely free to use on UtilityCove.
No. HTTP Status Code Reference runs in your browser, so your input stays on your device.
Yes. HTTP Status Code Reference works on modern mobile and desktop browsers.
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