Requirements
Lettern needs PHP 8.4 or newer, a database and a handful of standard extensions.
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#Server
| Requirement | Notes |
|---|---|
| PHP 8.4 or newer | PHP 8.5 is supported. |
| Database | MySQL 8, MariaDB 10.6+ or SQLite 3.35+. |
| Extensions | pdo with your database driver, mbstring, openssl, fileinfo, zip, curl, and gd or imagick for images. |
| Web server | Apache with .htaccess (shared hosting), Nginx, Caddy or PHP's built-in server for development. |
| Writable folders | The site folder, or at least storage/, config/, content/, plugins/, public/ and runtime/. |
| Network | Outgoing HTTPS, to fetch the release and plugins. |
The installer checks all of these and tells you exactly what is missing.
#Images
Lettern makes responsive WebP and AVIF variants of every uploaded image. AVIF needs GD built with AVIF support or Imagick; without it, Lettern serves WebP and the original.
#For plugin development
Building plugins with admin extensions needs Node.js 22+. Running and designing a site does not — releases carry their built assets, and the design lives in the CMS. Neither Composer nor Node is needed on the server.