Shibboleth is open-source software for single sign-on and identity federation, used by academic institutions, identity federations and commercial organisations. It is built on SAML and lets people use one identity to access systems run by member organisations in a federation. The software includes an Identity Provider for single sign-on, a Service Provider that offers authorisation and policy features and integrates with popular web servers, an Embedded Discovery Service and a Metadata Aggregator. It is downloaded and operated by the organisation itself, with documentation and support options available.
Development is coordinated by the Shibboleth Consortium, which is funded by membership fees. The software is licensed under Apache 2.0. Because you run Shibboleth yourself, you decide where identity data is processed and stored, and there is no dependence on a hosted service operated by a vendor. For European education and public-sector organisations, this means control over the sign-in infrastructure can stay entirely with the organisation itself.