Clerk

Clerk runs authentication and user management as a hosted service, and no self-hosted install is documented. Its security page states that data is hosted on US infrastructure and that regional data residency is not offered. Enterprise single sign-on covers SAML, OIDC and EASIE connections, and users are assigned to predefined Admin and Member roles, with custom roles and permissions on top of them.

Worth knowing

The client and server SDKs are separate open source packages next to the hosted service. The product documentation is on the docs site.