OpenAM!

LemonlLDAP::NG is a modular Web-SSO based on Apache::Session modules. It simplifies the build of a protected area with a few changes in the application. It manages both authentication and authorization and provides headers for accounting. So you can have a full AAA protection for your web space as described below.

The Shibboleth software implements widely used federated identity standards, principally the OASIS Security Assertion Markup Language (SAML), to provide a federated single sign-on and attribute exchange framework.

Keycloak is an open source identity and access management solution