WP Multisite compatible ?

This is a very good question which I’m interested learning as well. Thanks.

Yes. I’m using it on one of my MU sites. I’ve added user management (with support for MU) and a few other features here, https://github.com/monkeypunch3/JSON-API-Plus.

I have it setup as paths so https://www.mysite.com/blog/usersite_1, https://www.mysite.com/blog/usersite_2, etc.