Casbin

I would recommend Auth0 only if you are willing to shell out money. You can keep up with their free version only for a very limited time and as per our experience as a growing startup where budget is an issue, their support was not very helpful as they first asked us to sign a commercial agreement even before helping us t o find out whether Auth0 fits our use case or not! But otherwise Auth0 is a great platform to speed up authentication. In our case we had to move to alternatives like Casbin for multi-tenant authorization!