Its absolutely bonkers to me that web development has gotten to a point where this is a novel pitch. Up until not that long ago ALL auth was done directly in your own database and embeded in your own backend. Am I missing something?
Enterprise customers did the math on what a security breach lawsuit could cost and started demanding verifiably decent security, which meant some off-the-shelf off-premises solution.
That’s basically where we are now, and it’s the reason that most of Better Auth’s users are early-stage startups — they need to scale quickly, and they don’t have many pesky enterprise/governmental customers who might want to see a certification.
These days I tend to favor having auth built-in, via an "old school" web framework that provides an extensible auth system out of the box. Then we’ll extend that system with a managed 3rd party service to handle SAML when that starts to come up in sales conversations, because the setup is annoying and we can lean on the vendor to deal with whatever weird old IdP the client shows up with.