FishEye (software)

Fisheye is a revision-control browser and search engine owned by Atlassian, Inc. Although Fisheye is a commercial product, it is freely available to open source projects and non-profit institutions. In addition to the advanced search and diff capabilities, it provides:
 * the notion of changelog and changesets - even if the underlying version control system (such as CVS) does not support this
 * direct, resource-based URLs down to line-number level
 * monitoring and user-level notifications via e-mail or RSS

Use in open-source projects
Atlassian approves free licenses for community and open-source installations under certain conditions. Many major open source projects use Fisheye to provide a front-end for the source code repository:

Atlassian provides free licences of Fisheye and Crucible for open-source projects.

Integration
Fisheye supported integration with the following revision control systems:
 * CVS
 * Git
 * Mercurial
 * Perforce
 * Subversion

Due to the resource-based URLs, it is possible to integrate Fisheye with different issue and bug tracking systems. It also provides a REST and XML-RPC API. Fisheye also integrates with IDEs like IntelliJ IDEA via the Atlassian IDE Connector.