Feature-rich and lightning fast forums. Works standalone or as a Rails engine. Markdown by default, with plugins for code highlighting, KaTeX math, and BBCode. No JavaScript required. Easy deployment on Heroku or with Ansible. Format your posts with Markdown by default and / or BBCode, with onebox and <spoiler> tag support. 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: Pinned and locked topics. Private group messaging. (Un)read posts tracking. List of currently online users, global and per-messageboard. Page Speed score of 99+ / 100 in User Experience and 88+ / 100 in Speed on Mobile. 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, Chinese (Simplified), German, Polish, Italian, Russian, French, and Spanish.