Forum software rebuilt on the modern web stack: NodeBB runs the classic bulletin-board format - categories, threads, local accounts - in real time, on Node.js over MongoDB, Redis, or PostgreSQL. WebSockets stream new posts into open topics as they're written and deliver instant notifications for follows, likes, and subscriptions; built-in chat supports side-by-side private conversations. The headline of recent versions is core ActivityPub federation: your forum can follow, share, and converse with other NodeBB instances, Mastodon, Lemmy, and anything else that speaks the protocol, turning an isolated community into a fediverse node. Everything beyond the common core is a plugin - more than 500 plugins and themes install in one click from the admin panel, covering SSO providers, search backends like Elasticsearch and Solr, galleries, calendars, and more. The theming engine extends base templates with SCSS/CSS on Bootstrap 5, plus a drag-and-drop widget system and custom HTML/CSS/JS injection. Operators get a real-time analytics dashboard, human-readable SEO-friendly URLs with semantic markup, multilingual UI, and full read and write REST APIs for integration. Mobile-first rendering means the same install works everywhere. For communities that outgrew phpBB but don't want Discourse's weight, NodeBB is the natural middle.