We support the following:
SAML (Security Assertion Markup Language)
Open ID Connect
Google G-Suite
Microsoft Azure Active Directory (often abbreviated to Azure AD)
Active Directory Federated Services (ADFS)
Active Directory/LDAP (Lightweight Directory Access Protocol)
Ping Federate
The majority of Identity Providers (the system managed by the customer that authenticates the user) will support SAML and this is our preferred means of implementing SSO.