SimpleSAMLphp is an authentication application written in native PHP. It focuses on SAML 2.0 and can act as a service provider or an identity provider; it also supports CAS, OpenID Connect, WS-Federation and OAuth. It provides single sign-on and federated login and can be extended with custom modules. It is used to connect web applications to federated identity infrastructure and as a proxy between identity providers. You install and operate it yourself on a web server with PHP.
SimpleSAMLphp is open source under the LGPL-2.1 and is maintained by a community of contributors; it was originally developed by staff of Uninett, the Norwegian research network. There is no vendor-hosted service, so no vendor holds your data: the location and jurisdiction of user accounts and sessions follow from where you deploy it. A European organisation can run it on its own or EU infrastructure and review the code itself. NLnet funded work on the project in 2025.