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.
Nibbleblog - Nibbleblog is a powerful engine for creating blogs, all you need is PHP to work.
Grav - The modern open source flat-file CMS
razorCMS - razorCMS is a file based CMS (Content Management System), allowing you to create a website in a graphical way without the need of a separate database.
Bludit - Bludit is a web application to build your own website or blog in seconds, it's completely free and open source. Markdown support.
Drupal - Drupal - the leading open-source CMS for ambitious digital experiences that reach your audience across multiple channels. Because we all have different needs, Drupal allows you to create a unique space in a world of cookie-cutter solutions.