Google App Engine is a powerful system, designed to take all the pain of infrastructure management and performance scaling out of web application programming. Thoughtsite is a discussions/forum web app designed for Google App Engine, and is an open source using Apache 2 license. Features: a flexible system that could be used for any kind of discussion forum; voting, tagging, comments and a reputation point system for users; full text search on App Engine with Apache Lucene; search for threads by tags or by keywords. Threads can also be linked to from user profiles; users gain reputation points based on community votes for their contributions; full-fledged user profiles with info, points, contributions, user's personal tag cloud, etc; basic duplication detection filters to detect similar threads so posters can avoid creating a new thread if one already exists; basic spam and gaming filters (self-voting, cross-voting, etc.); comprehensive admin section that allows moderation of individual posts and users. Users can flag objectionable content or trolls.
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