OAIster is an online combined bibliographic catalogue of open access material aggregated using OAI-PMH. It began at the University of Michigan in 2002 funded by a grant from the Andrew W. Mellon Foundation and with the purpose of establishing a retrieval service for publicly available digital library resources provided by the research library community. During its tenure at the University of Michigan, OAIster grew to become one of the largest aggregations of records pointing to open access collections in the world.