Hugo is a Fast and Flexible Static Site Generator

Jekyll is a simple, blog-aware, static site generator.

Kirby is a file‑based CMS Easy to setup. Easy to use. Flexible as hell.

la.plume is a small, open source flat file system to build fast, simple websites

Mara CMS performs a similar core function to 'Content management systems' like Drupal or Wordpress - although it differs in many fundamental aspects from those packages. Probably the most significant difference is its being file based instead of database dependent.

Mecha is a file-based CMS.