FreeRadius - FreeRADIUS is responsible for authenticating one third of all users on the Internet.
JumpCloud - Cloud-based directory services. Alternative to Microsoft Active Directory.
Microsoft Azure Active Directory - Azure Active Directory is a comprehensive identity and access management cloud solution that provides a robust set of capabilities to manage users and groups and help secure access to applications including Microsoft online services like Office 365 …
FusionAuth - FusionAuth is a CIAM platform that is 100% free for unlimited users.
OneLogin - On-demand SSO, directory integration, user provisioning and more
OpenLDAP - OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.