> - Keycloak (you won't get fired for picking this)[0]
Curious what you mean with "you won't get fired for picking this". Do you mean that it's good and easy to run, or something else?
If you are looking for a commercial solution, I would say that the top competitors are Okta, Auth0, Azure AD, and Firebase (though the latter, from what I've heard, doesn't play nicely with standards).
I mean, it's yet to be determined how Okta and Auth0 are going to integrate. I have read that Okta has three sets of APIs, maybe Auth0 will be a fourth?
> an enterprise client is probably not going to use your product because it has Firebase login integration.
LOL. It might even be a negative signal.
But I hear Firebase is thinking about supporting standard OAuth, which would be great.
Okta bought Stormpath (and killed it) and now Auth0 because of this difference, and because there's a finite total addressable market for employees, but an almost infinite total addressable market for app users.
And as others have noted, this is probably the most enterprise-grade/production-hardened solution out there in the list that I made that represents my current list in the F/OSS space. If I were to think hard about it, there are probably lots of much older options (depends on where you put the scope of AuthN to be, is LDAP a competitor?), but Keycloak is probably the one you're going to find the most resources and scrutiny around.
A large financial institution I worked with two years ago was using Keycloak. I was annoyed with some UI bits and terminology that was very confusing but it was overall a great choice back then IMO, has probably mostly/only gotten better since.