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LensKit is free and open-source software, available under the terms of the GNU Lesser General Public license version 2.1 or later.


LensKit development began at GroupLens Research at the University of Minnesota and is now coordinated by the People and Information Research Team (PIReT) at Boise State University. We welcome contributions from developers anywhere. LensKit work is made possible by support from a number of organizations:

  • Multiple GroupLens Research projects, particularly MovieLens and BookLens, use LensKit in production, providing experience, bug reports, and other valuable feedback (and code). We also maintain list of LensKit users.
  • Development has been funded in part by the National Science foundation (under grants IIS 05-34939, 08-08692, 08-12148, and 10-17697).
  • YourKit is kindly supporting the project with free licenses for the YourKit Java profiler.