Running alongside separate authed API?

Has anyone ran WASP front end alongside a separate API? My plan is to run WASP as the front end interface to a data visualization app and manage paying users in it. I have a standalone data API server already in place. My thought is that my other data API would need to interface with the WASP user management system to make sure that users requesting data and certain pages are actually at the right user tier to do that. Does anyone know if that's possible? Perhaps I could have my data API reading user rights from the same database or just calling a WASP api of some sort?