Most “lightweight” forums cut corners. FlatBB is different: plain PHP 8.1+, no Composer/Docker/build step — but the feature list is what small communities actually need.
Interface packs ship in the box: Also:
Discussion: nested categories (one level) + per-group permissions, tags, topics/replies, quotes, @mentions, Markdown + live preview, drag/paste image upload, likes, bookmarks, unread tracking, notifications.
Discovery: full-text search (SQLite FTS5 / MySQL FULLTEXT), Latest / Top / Unread, clean URLs, RSS, sitemap, profiles & avatars.
UX: Discourse/Flarum-style three-column layout that collapses on phones, dark mode, one-click upgrades.
Admin: settings, categories, tags, users, groups, layout blocks, plugins, scheduled jobs, tools.
Need more? The marketplace and AI-friendly plugin API cover SEO, social login (Google/GitHub/X), Q&A, levels, verified badges, Guard/2FA, drafts, and more. Plugin docs for assistants: https://www.flatbb.com/dev/plugins.md
MIT licensed. If you try it, tell us where it breaks — the support forum runs on FlatBB itself.