OmniAuth provides authentication federation at the language (Ruby) level, with a [wide range of integrations](https://github.com/intridea/omniauth/wiki/List-of-Strategies) available.
### [Okta](http://developer.okta.com/product/)
Okta is a commercial product which is similar to dex in that for it too, identity federation is a key feature. It connects to many more authentication providers than dex, and also does the federation in the oppposite direction - it can be used as a SSO to other identity providers.
### [Shibboleth](https://shibboleth.net/)
Shibboleth is an open source system implementing the [SAML](https://www.oasis-open.org/standards#samlv2.0) standard, and can federate from a variety of backends, most notably LDAP.