Huggle is a fast diff browser application intended for dealing with vandalism on Wikimedia projects, written in C++. It was originally developed in .NET by Gurch, who is no longer active on this project. Anyone can download Huggle, but rollback permission is required to use it in unrestricted mode on English Wikipedia.
Huggle is able to load and review edits made to Wikipedia in real time, helps users identify unconstructive edits, and allows them to be reverted quickly. Various mechanisms are used to draw conclusions to whether an edit is constructive or not. It uses a semi-distributed model where edits are retrieved using a "provider" (this can be anything that is capable of distributing a stream of edit information, such as the Wikipedia API or IRC recent changes feed), pre-parse and analyze these edits and share the information with other tools, such as ClueBot NG. Huggle also uses a number of self-learning mechanisms, including a global white-list (users that are considered trusted) and user-badness scores that are stored locally on the client's computer.
Note: It is possible to install Huggle on 3rd party sites as well. If you are a maintainer of a MediaWiki wiki and you wish to use Huggle there, please follow the manual for deployment of Huggle.