Batflat - Lightweight, fast, easy, and free CMS.
Grav - The modern open source flat-file CMS
Shopping feed - Shopping feed is a versatile eCommerce application that allows eCommerce stores to thousands of channels.
WordPress - WordPress is web software you can use to create a beautiful website or blog. We like to say that WordPress is both free and priceless at the same time.
ImpressPages CMS - ImpressPages is a PHP framework with admin panel.
Fansoro - Fansoro is a Modern Open Source Flat-File Content Management System.