HTTP Status Codes
Every status code developers actually encounter, organized by category.
1xxInformational
100Continue
Server received the request headers; client should proceed to send the body.
Common use: Large file uploads with Expect: 100-continue header.
101Switching Protocols
Server is switching protocols as requested by the client.
Common use: WebSocket upgrade handshake.
103Early Hints
Lets the browser start preloading resources while the server prepares a response.
Common use: Preloading CSS/JS before final response.
2xxSuccess
200OK
The request succeeded. Response body contains the requested resource.
Common use: Standard successful GET, PUT, or PATCH response.
201Created
The request succeeded and a new resource was created.
Common use: POST request that creates a new record. Return Location header.
202Accepted
The request was accepted for processing, but processing is not complete.
Common use: Async operations like batch jobs or email sending.
204No Content
The request succeeded but there is no content to return.
Common use: Successful DELETE request or PUT with no response body needed.
206Partial Content
Server is delivering only part of the resource due to a Range header.
Common use: Video streaming, resumable file downloads.
3xxRedirection
301Moved Permanently
The resource has been permanently moved to a new URL.
Common use: Domain migration, URL restructuring. Search engines update their index.
302Found
The resource temporarily resides under a different URL.
Common use: Temporary redirects during maintenance. Often misused instead of 303/307.
303See Other
Response to the request can be found at another URL using GET.
Common use: Redirect after POST form submission (Post/Redirect/Get pattern).
304Not Modified
The resource has not been modified since the last request.
Common use: Browser cache validation with If-None-Match or If-Modified-Since.
307Temporary Redirect
Same as 302 but the HTTP method must not change.
Common use: Temporary redirect that preserves POST method and body.
308Permanent Redirect
Same as 301 but the HTTP method must not change.
Common use: Permanent redirect that preserves POST method and body.
4xxClient Error
400Bad Request
The server cannot process the request due to malformed syntax.
Common use: Invalid JSON body, missing required fields, validation failures.
401Unauthorized
Authentication is required and has failed or not been provided.
Common use: Missing or expired JWT token, invalid API key.
403Forbidden
The server understood the request but refuses to authorize it.
Common use: User is authenticated but lacks permission for this resource.
404Not Found
The server cannot find the requested resource.
Common use: Resource does not exist at this URL. Check for typos.
405Method Not Allowed
The HTTP method is not supported for this resource.
Common use: Sending POST to a read-only endpoint. Include Allow header in response.
406Not Acceptable
The server cannot produce a response matching the Accept headers.
Common use: Client requests XML but API only serves JSON.
408Request Timeout
The server timed out waiting for the request.
Common use: Client took too long to send the complete request.
409Conflict
The request conflicts with the current state of the resource.
Common use: Duplicate entry, optimistic concurrency conflict, version mismatch.
410Gone
The resource was once here but has been permanently removed.
Common use: Deprecated API endpoint. Unlike 404, this is intentional and permanent.
411Length Required
The server requires a Content-Length header.
Common use: Chunked uploads to servers that need content length upfront.
413Content Too Large
The request body exceeds the server limit.
Common use: File upload exceeds max size. Previously called Payload Too Large.
415Unsupported Media Type
The media type of the request body is not supported.
Common use: Sending form data to an endpoint that only accepts JSON.
418I'm a Teapot
The server refuses to brew coffee because it is a teapot.
Common use: RFC 2324 April Fools joke. Sometimes used as an Easter egg.
422Unprocessable Content
The request is well-formed but contains semantic errors.
Common use: Valid JSON but business logic validation fails (e.g., end date before start date).
429Too Many Requests
The user has sent too many requests in a given time period.
Common use: Rate limiting. Include Retry-After header to indicate when to retry.
451Unavailable for Legal Reasons
Access is denied for legal reasons such as censorship or court order.
Common use: GDPR content restrictions, government-mandated blocks.
5xxServer Error
500Internal Server Error
The server encountered an unexpected condition that prevented it from fulfilling the request.
Common use: Unhandled exception, null reference, database connection failure.
501Not Implemented
The server does not support the functionality required to fulfill the request.
Common use: Unsupported HTTP method or feature not yet built.
502Bad Gateway
The server, acting as a gateway, received an invalid response from the upstream server.
Common use: Reverse proxy (nginx, Cloudflare) cannot reach the origin server.
503Service Unavailable
The server is not ready to handle the request, usually due to maintenance or overload.
Common use: Planned maintenance, server overload. Include Retry-After header.
504Gateway Timeout
The server, acting as a gateway, did not get a response from the upstream server in time.
Common use: Origin server is too slow. Check for long-running queries or deadlocks.