Statamic is an open-source flat-file CMS built on Laravel, originating in 2012, known for database-free, Git-friendly content management, with free Core and one-time $349 per-site Pro licensing.
Pico CMS is a lightweight open-source flat-file CMS first released in 2013, storing content as Markdown files and rendering pages with Twig templates on any PHP host with millisecond-level page loads, ideal for personal blogs, portfolios and lightweight documentation sites.
Grav is an open-source flat-file CMS developed by the RocketTheme team, with no database, Markdown file storage, a free MIT license, lightweight deployment, and multilingual support for documentation and light content sites.
CouchCMS is a content management system released in 2011 that runs without a database, embedding editable regions into existing static pages via HTML tags, ideal for designers building lightweight sites for small-to-medium clients.