This interim response indicates that everything so far is OK and that the client should continue the request, or ignore the response if the request is already finished.
101 Switching Protocol
This code is sent in response to an
Upgrade request header from the client, and indicates the protocol the server is switching to.
102 Processing (WebDAV)
This code indicates that the server has received and is processing the request, but no response is available yet.
103 Early Hints
This status code is primarily intended to be used with the
Link header, letting the user agent start preloading resources while the server prepares a response.