Evergreen

The Evergreen Project develops an open source ILS (integrated library system) used by more than 2,000 libraries around the world. The software, also called Evergreen, is used by libraries to provide their public catalog interface as well as to manage back-of-house operations such as circulation (checkouts and checkins), acquisition of library materials, and (particularly in the case of Evergreen) sharing resources among groups of libraries.

The Evergreen Project was initiated by the Georgia Public Library System in 2006 to serve their need for a scalable catalog shared by (as of now) more than 275 public libraries in the state of Georgia. After Evergreen was released, it has since been adopted by a number of library consortia in the US and Canada as well as various individual libraries, and has started being adopted by libraries outside of North America. The Evergreen development community is still growing, with about eleven active committers and roughly 80 individuals who have contributed patches (as of April, 2016). However, the Evergreen community is also marked by a high degree of participation by the librarians who use the software and contribute documentation, bug reports, and organizational energy. As such, Evergreen is very much about both the developers and the users.

Source: https://evergreen-ils.org/about-us/