This looks like an interesting concept. How does it compare with LDAP/Active Directory/Google Apps integration?
Onboarder is definitely not that complex yet, but I'm still learning about this space. My goal was to make it simple. Connect with OAuth or give us an API key, and we're good to go.
The onboarding/offboarding process is generally initiated from there, and internal apps and services tend to use that as the canonical user store.
Good luck with your project, I hope it works out well for you!