FOLIO, an acronym for Future of Libraries is Open, is an open-source library services platform that combines APIs from multiple backend microservices with a frontend Javascript single-page Application.
Academic, public, and national libraries use FOLIO, either through a managed hosting service or by hosting it on-site. Stanford University Libraries migrated to a self-hosted FOLIO installation in 2023. The Library of Congress is currently migrating to FOLIO, with other notable academic libraries like the University of Chicago and Cornell University already using FOLIO.
A major refactoring of FOLIO's backend, called Eureka, is being led by EBSCO, a major code contributor and hosting provider for FOLIO. Eureka replaces FOLIO's current bespoke API gateway, Okapi, with a combination of open-source products, Kong and Keycloak that will make FOLIO more scalable and robust.