CILogon provides a software platform that enables scientists to work together to meet their identity and access management (IAM) needs more effectively so they can allocate more time and effort to their core mission of scientific research. CILogon builds on open source Shibboleth and COmanage software to provide an integrated IAM platform for science, federated worldwide via eduGAIN. CILogon serves the unique needs of research collaborations, namely to dynamically form collaboration groups across organizations and countries, sharing access to data, instruments, compute clusters, and other resources to enable scientific discovery. We operate CILogon via a software-as-a-service model to ease integration with a variety of science applications, while making all CILogon software components publicly available under open source licenses to enable re-use. Since CILogon operations began in 2010, our service has expanded from a federated X.509 certification authority (CA) to an OpenID Connect provider, SAML Attribute Authority, and multi-tenant collaboration platform. In this article, we describe the current CILogon system.