What auth solutions are you using in your apps? Why them? (Auth0, Firebase, etc)

Hello people!

I've seen a great thread at https://www.indiehackers.com/post/are-you-guys-using-solutions-such-as-auth0-to-authenticate-and-manage-users-c14897a872

I'd like to discuss this topic in more depth and with a broader perspective.

The questions are in the title. Let's drop some names here and reasons for choosing them for your apps and teams.

Cheers!