100 Continue
The server has the request headers and the client should go on and send the body. The reply to Expect: 100-continue, so a large upload can be turned away before it is sent.
- Class
- 1xx Informational. An interim response, sent before the final one.
- Registered
- Yes, in the IANA HTTP status code registry.
- References
- RFC 9110 ยง15.2.1 · MDN