Azure Active Directory is described as 'comprehensive identity and access management cloud solution that provides a robust set of capabilities to manage users and groups'. There are more than 10 alternatives to Azure Active Directory, not only websites but also apps for a variety of platforms, including Windows, Self-Hosted solutions, Mac and SaaS. The best alternative is Keycloak, which is both free and Open Source. Other great sites and apps similar to Azure Active Directory are Okta (Freemium), OneLogin (Paid), Microsoft Active Directory (Paid) and Ory (Free, Open Source).
Ory builds cloud-native authentication (login), authorization (permission), delegation (OAuth2, OpenID Connect), and user management software. You can deploy what you need yourself or use the Ory Cloud Platform and get started in minutes.
Cloud-based directory services. Alternative to Microsoft Active Directory. Provides LDAP-as-a-Service, RADIUS-as-a-Service. Authenticates, authorizes, and manages employees, their devices and IT applications.