Strapi is an open-source headless CMS founded in Paris, France in 2015, leading its category with 65,000+ GitHub stars. Its visual content type builder auto-generates REST/GraphQL APIs with self-hosting and Strapi Cloud options.
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.
TYPO3 is an enterprise open-source CMS founded in 1997 and headquartered in Düsseldorf, Germany, known for native multilingual support, fine-grained permissions, and 5000+ extensions, a top choice for large enterprises and institutions in German-speaking Europe.
Textpattern is a lightweight open-source PHP CMS released in 2003, known for semantic templates and Textile typesetting with a small footprint and SEO-friendly output, suited to personal blogs and light content sites.