Ya, just implement a web server in your application and you’ll be set 
. I kid.
You’re going to want to hit the API on an interval to detect new subs, and probably cache them to an extent. Keep in mind it won’t be “real time” like webhooks are, but it should be sort of close.
You’re probably interested in https://dev.twitch.tv/docs/v5/reference/channels#get-channel-followers