What authentication system/provider are you using for logins?

Check out this older thread with a lot of perspectives in the comments: https://www.indiehackers.com/forum/how-do-you-handle-user-signups-or-logins-85962774e4

Thanks for all the answers. In the end I wrote myself an STS Micro-service. Too much work but hey, good practice.

Now I need to find a cheap SMTP email provider to build myself an email Micro-service to send the new account confirmations etc. Just doing these two things makes me see that both authentication AND email services out there are all too expensive (hundreds of dollars to send a few thousand emails???)

There's definitely space in these two markets for lower cost solutions, then again I'm not sure if I would want to make that my specialty (there's a real issue with finding an internet provider that will allow setting up an email service too, I think...)

To me sending 25000 emails per month should cost peanuts. It seems the market disagrees with me, ha ha ha.

Firebase auth gives you tons of auth options including support for gsuite and office365 enterprise accounts.

Then you could just pass an auth token to your API, and use their firebase auth server side SDK to get user details and cryptographically validate the token in just a few lines of code.

I am using Auth0. It saves me a lot of time, and I am sure that I have a secure system in place. Once costs become a problem, I can always re-consider... my 2ct