Haven’t done any research in that department yet. I have some experience with REST APIs in Django and Flask, but pre-built solutions are quite enticing. I will obviously have to use some kind of login API as I do not trust myself with securely storing passwords (crypto 101 class nonwithstanding), so why not outsource the whole multiplayer aspect? 
Multiplayer probably won’t be part of the initial release though, the only thing on that list that we plan to include is the crafting system, a demo of which I would like to have completed by the end of June (have to tackle the final undergrad exams first).