Netlify CMS - An open-source CMS for your Git workflow
PHPmaker - PHPMaker is a powerful automation tool that can generate a full set of PHP quickly from MySQL, PostgreSQL, Oracle, Microsoft Access, Microsoft SQL Server and SQLite databases.
Cloud Cannon - Cloud Cannon turns Dropbox/Git-project into a CMS you can setup in seconds
P4A - Php For Applications - PHP5 RAD Framework based on Zend Framework.
Sanity.io - Sanity.io a platform for structured content that comes with an open-source editor that you can customize with React.js.
MT Backend - MT backend is a PHP control panel solution for websites.