Bludit - Bludit is a web application to build your own website or blog in seconds, it's completely free and open source. Markdown support.
Cloud Cannon - Cloud Cannon turns Dropbox/Git-project into a CMS you can setup in seconds
Grav - The modern open source flat-file CMS
Netlify CMS - An open-source CMS for your Git workflow
HTMLy - HTMLy is an open source databaseless blogging platform. A Flat-File Blog and Flat-File CMS written in PHP prioritizes simplicity and speed.
Strapi - Strapi is the most advanced Node.