Ask HN: Your goto authentication for side projects?

[need_the_auths]

Authentication and user management is a real pain when all you want to do is work on the core aspects of your project. I used to use Mozilla's Persona (but they have stopped supporting it) and Meteor has a great solution to getting it done fast, but isn't language or even framework agnostic.

I've been looking around at others, but none are as turn key as those two.

So what is your goto for getting it done quickly at the alpha/beta stage?