Blacklight is an open-source Ruby on Rails engine for creating search interfaces on top of Apache Solr indices.

The software is used by libraries to create discovery layers or institutional repositories; by museums and archives to highlight digital collections; and by other information retrieval projects.

The University of Virginia began developing Blacklight based on its Collex scholarly publishing software, which also used Ruby and Rails and Solr.

[2] The goals of the project included improving the user experience over contemporary OPAC systems, particularly with regard to relevance ranking, and showcasing historically underutilized library collections.

[5] There are several plugins available for Blacklight as well, including an extension for geospatial data,[6] a digital exhibit creation tool,[7] and various search and user interface features.