Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
Anvil.io - Identity is the missing link that connects all your users, apps, services, and devices to each...
Keycloak - Open Source Identity and Access Management for modern Applications and Services.
AdiInviter Pro - The ultimate contacts importer and tell-a-friend system for your website.
Okta - Enterprise-grade identity management for all your apps, users & devices
OmniAuth - OmniAuth is a flexible authentication system utilizing Rack middleware.