Core is a project mainly written in PHP, based on the GPL-3.0 license.
Meridian Framework Core
Meridian is a PHP framework that runs on PHP and MySQL (if you want to use a database).
Meridian's development status is currently extremely low. Why? I'm pursuing other projects that aren't written in PHP.
Meridian requires PHP and if you want to use the database, MySQL.
While designed to run on a server with mod_rewrite or equivalent it's quite possible it might run without it.