503 Service Unavailable

Not now. We're fucked.

What it properly means

The server is not ready to handle the request, usually because it is down for maintenance or overloaded. Should be temporary, ideally with a Retry-After header.

Class
5xx Server error: we fucked up
Defined in
RFC 9110, section 15.6.4

Get one yourself

This endpoint really answers with 503. Point your client at it and see what it does.

curl -i https://httpcodes.dev/api/503

People mix this up with

  • 429 Too Many Requests503

    Is it you, or is it us?

    429 blames the client: you personally are sending too much. 503 blames the server: it is overloaded or down for everyone.

  • 500 Internal Server Error503

    Broken, or just busy?

    500 means something went wrong that nobody planned for, usually a bug. 503 means the server is knowingly unavailable for now and you should try again later.