Metalsmith - An extremely simple, pluggable static site generator.
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Nikola - Nikola is s static site generator tool written in Python.
Anchor CMS - Free and lightweight blogging system
GatsbyJS - Blazing-fast static site generator for React
Textpattern - Textpattern is an elegant content management system that is free, open source software.