The Lemur Project

The Lemur Project develops search engines, browser toolbars, text analysis tools, and data resources that support research and development of information retrieval and text mining software. The project is best known for its Indri search engine, Lemur Toolbar, and ClueWeb09 dataset. Our software and datasets are used widely in scientific and research applications, as well as in some commercial applications.

The Lemur Project's software development philosophy emphasizes state-of-the-art accuracy, flexibility, and efficiency. For example, the Indri search engine provides accurate search for large text collections 'out of the box', and data is stored in an accessible manner to support development of new retrieval strategies. Software from the Lemur Project is distributed under open-source licenses that provide flexibility to scientists and software developers.

The Lemur Project was begun by the Center for Intelligent Information Retrieval (CIIR) at the University of Massachusetts, Amherst, and the Language Technologies Institute (LTI) at Carnegie Mellon University. For more information about the Lemur Project, see the About page.









6/22/2020 - Released: Lucindri 1.1, Indri 5.17, Galago 3.18, RankLib 2.14 and Sifaka 1.8



Updates and bug fixes occur throughout the year. See the current release notes for complete details.

