Flatbb

What is Flatbb?

Flatbb is a flat, lightweight forum in plain PHP 8: no framework, no Composer, no build step. Unzip it into a web folder, open the URL, and the installer sets up SQLite or MySQL. It runs on the cheapest shared hosting. Categories, tags, markdown, mentions, attachments, notifications, search, dark mode and a mobile layout are built in. Plugins are one folder you upload in the admin panel, and the whole plugin API fits in one text file you can hand to Claude, Codex or Cursor. MIT licensed.