Okta - Enterprise-grade identity management for all your apps, users & devices
FusionAuth - FusionAuth is a CIAM platform that is 100% free for unlimited users.
OneLogin - On-demand SSO, directory integration, user provisioning and more
Ping Identity - Ping Identity provides cloud-based, single sign-on and identity management solutions with their SAML SSO.
Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
Atlassian Crowd - Crowd is a single sign-on and user identity solution.