HTTP Status Code Lookup
Search common HTTP response codes by number or meaning.
18 statuses
What it means
Server received the request headers and client may continue sending the request body.
Use it when
Rarely sent by application code; useful for large uploads when the client sends Expect: 100-continue.
Example
A client checks that the server will accept a large upload before sending its body.
What it means
Request completed successfully.
Use it when
Use for successful reads, updates, or actions that return a response body.
Example
GET /users/42 returns the user document.
What it means
Request succeeded and created a new resource.
Use it when
Use after a successful POST or another operation that creates a resource.
Example
POST /projects creates a project and returns its URL in Location.
What it means
Request succeeded, but there is no response body to return.
Use it when
Use for successful deletes or updates when the client already has everything it needs.
Example
DELETE /sessions/current succeeds without returning JSON.
What it means
Resource now has a permanent canonical URL.
Use it when
Use when changing a public URL and you want browsers and search engines to update their links.
Example
/old-docs permanently redirects to /docs.
What it means
Cached representation is still fresh, so the server sends no body.
Use it when
Return after If-None-Match or If-Modified-Since matches the current resource.
Example
A browser revalidates a stylesheet and reuses its cached copy.
What it means
Server cannot process the request because its syntax or parameters are invalid.
Use it when
Use for malformed JSON, invalid query parameters, or a request that cannot be interpreted.
Example
POST /orders sends invalid JSON or a malformed date value.
What it means
Request needs valid authentication credentials.
Use it when
Use when credentials are missing, expired, or invalid. Include a WWW-Authenticate challenge when applicable.
Example
An API request has no access token, so the client must sign in first.
What it means
Server understood the request but refuses to authorize it.
Use it when
Use when the caller is authenticated but lacks permission for the resource or action.
Example
A viewer attempts to delete a project owned by another team.
What it means
Server cannot find a current representation for the requested URL.
Use it when
Use for unknown routes or resources that do not exist. Avoid exposing whether sensitive records exist.
Example
GET /invoices/9999 references an invoice that is not available.
What it means
Resource exists, but the HTTP method is not supported for it.
Use it when
Use when a route supports GET but receives an unsupported method such as PATCH.
Example
POST /health is rejected because the endpoint only supports GET.
What it means
Server waited too long for the client to finish sending its request.
Use it when
Use when an idle client connection times out before a complete request arrives.
Example
An upload connection stops sending data for longer than the server limit.
What it means
Request conflicts with the current state of the target resource.
Use it when
Use for edit collisions, duplicate names, or state transitions that are no longer valid.
Example
Two users update the same document version and the second write loses the race.
What it means
Client exceeded a rate limit in a given period.
Use it when
Use for throttling. Include Retry-After when the client can safely retry later.
Example
A public API blocks a client after too many requests per minute.
What it means
Server hit an unexpected condition while handling the request.
Use it when
Use as a safe fallback for unhandled application errors. Log details privately, not in the response.
Example
A database exception escapes a request handler.
What it means
Gateway or proxy received an invalid response from an upstream server.
Use it when
Use at a reverse proxy when the upstream service responds with an invalid or unexpected payload.
Example
An API gateway cannot parse a response from a service it calls.
What it means
Server is temporarily unable to handle the request.
Use it when
Use during maintenance, overload, or a temporary dependency outage. Add Retry-After if useful.
Example
A service is deploying and briefly removes itself from the load balancer.
What it means
Gateway did not receive a timely response from an upstream server.
Use it when
Use when a proxy or gateway gives up waiting for a dependency.
Example
A checkout gateway times out while waiting for the payment provider.