FreeIPA is described as 'Integrated security information management solution combining Linux (Fedora), 389 Directory Server, MIT Kerberos, NTP, DNS, Dogtag (Certificate System). It consists of a web interface and command-line administration tools' and is an app in the network & admin category. There are more than 10 alternatives to FreeIPA for a variety of platforms, including Linux, Self-Hosted, Windows, Mac and Web-based apps. The best FreeIPA alternative is Keycloak, which is both free and Open Source. Other great apps like FreeIPA are authentik, Microsoft Active Directory, AWS Identity and Access Management and Tinyauth.
FreeIPA has many more services, but SSO isn't one of them.