Statamic - Build better, easier to manage websites. Enjoy radical efficiency. It's everything you never knew you always wanted in a CMS.
Bludit - Bludit is a web application to build your own website or blog in seconds, it's completely free and open source. Markdown support.
HubSpot Website Platform - HubSpot Website Platform is a content management system that enables marketers to build websites personalized for every visitor.
WonderCMS - WonderCMS is the smallest flat file CMS. Completely free, open source, privacy oriented for over 12 years.
Craft CMS - Content management system built on Yii PHP Framework
Grav - The modern open source flat-file CMS