Install a forum on $2 shared hosting in 2 minutes: no Composer, no Docker, no build step

Most forum software today assumes you have a build pipeline. Discourse wants Ruby, Docker, Redis and Postgres. Flarum is PHP but still needs Composer and a terminal. That is fine for a company running a big community, but it rules out the hosting most small communities actually have: a $2 shared plan with a file manager and a MySQL database.

Flatbb is a flat, lightweight forum I wrote for exactly that case. Plain PHP 8, no framework, no Composer, no build step, MIT licensed. This post is the whole installation, then the part I find more interesting: writing plugins for it with an AI assistant.

What you need

• Any host with PHP 8.1 or newer (pdo_sqlite or pdo_mysql, mbstring)
• A MySQL 5.7+ database, or nothing at all if you use SQLite
• A way to put files on the server: FTP, the hosting file manager, or unzip over SSH if you have it

Step 1: download and unzip

Get the zip from https://www.flatbb.com/download and unzip it. You get one folder, flatbb-0.1.10/. Rename it to whatever you like or put its contents straight into your web root.

public_html/
  index.php
  core/
  app/
  assets/
  plugins/
  data/        <- config and SQLite file live here, must be writable
  uploads/     <- attachments and avatars, must be writable

If your host lets you set the document root, point it at the folder. If not, the root works too; data/ and uploads/ are protected by the bundled .htaccess (Apache) and the nginx rules in the docs.

Step 2: open the URL

Visit your domain. The installer appears:

1. Choose the language.
2. Choose MySQL (enter host, database, user, password) or SQLite (nothing to enter).
3. Create the admin account.

That is the deployment. There is no step 3. The whole thing took under two minutes on a cheap shared plan when I timed it.

What you get

Categories, tags, flat topics with replies, markdown with mentions and attachments, notifications, full-text search (FTS5 on SQLite, FULLTEXT on MySQL), dark mode, a three-column layout that collapses to one on a phone, and an admin panel for users, groups, categories, layout blocks and plugins. Seven language packs ship in the box.

Upgrades are one click: Admin, Tools, Check for updates. The core is a handful of small PHP files you can read in an afternoon, which matters when something breaks on a host you cannot SSH into.

Plugins: one folder, one manifest

Everything beyond the core is a plugin. A plugin is a folder with a plugin.php that returns a manifest: routes, hooks, settings, admin pages, scheduled jobs, and its own tables through helpers that work on both SQLite and MySQL.

<?php
return [
    'id' => 'hello',
    'name' => 'Hello',
    'version' => '1.0.0',
    'description' => 'Shows a greeting above the topic list.',
    'hooks' => [
        'region.home.top' => 'hello_banner',
    ],
];

function hello_banner(string $html, array $ctx): string
{
    return $html . '<div class="hello-banner">' . h(t('Welcome!')) . '</div>';
}

You install a plugin by uploading the zipped folder in Admin, Plugins, or in one click from the marketplace at https://www.flatbb.com/market.

Writing plugins with an AI assistant

Because the plugin API is small, it fits in a single text file: https://www.flatbb.com/dev/plugins.md. That file is the spec, the hook list and the helper reference in one.

The workflow I use:

1. Paste the URL above into Claude Code, Codex or Cursor.
2. Describe the plugin: what it does, where it shows up, its settings, who may use it.
3. Ask for the finished folder as a zip.
4. Upload it under Admin, Plugins.

The assistant gets the naming rules (hello_* functions, plugin_hello_* tables, .hello-* CSS), the security rules (escape with h(), never read superglobals, POST plus CSRF for every state change) and the portability rules (no engine-specific SQL) from the same document, so the result usually passes php flatbb plugin:check first time. Every bundled plugin was built this way.

Links

• Download: https://www.flatbb.com/download
• Source on GitHub: https://github.com/nwnuyhs/flatbb
• Plugin marketplace: https://www.flatbb.com/market
• Plugin docs for AI assistants: https://www.flatbb.com/dev/plugins

If you try it, tell me where it breaks. The support forum runs on Flatbb itself, which is the best test I know.