Format your posts with Markdown by default.
Never miss an update with @-mentions, email notifications, and (un)read posts tracking.
Enjoy the fully-responsive minimalistic theme, configurable via Sass.
Find posts quickly with full-text search, using only the database.
Stop the trolls with a basic moderation system.
Thredded also has:
Thredded has no infrastructure dependencies other than the database.
Currently, Thredded supports SQLite, MySQL v5.6.4+, and PostgreSQL.
Thredded can be easily integrated into the rest of your Rails app as an engine, and will work with your existing auth. There is also a one-step app generator that can create a new Rails app with Thredded.
Thredded has been built for extensibility, and provides a modular post rendering pipeline, flexible permissions system.
Thredded uses i18n throughout and has been translated into Brazilian Portuguese, Polish, Russian, French, and Spanish.
See the source code on GitHub.