Strapi is an open source headless CMS on Node.js that auto-generates REST and GraphQL APIs from any content model you define. Self-host or use Strapi Cloud.
Open source alternatives to Contentful
2 free, self-hostable tools you can use instead of Contentful, sorted by GitHub stars.
Alternatives to Contentful 2
Grav
Replaces Contentful
Build content-driven websites with a fast flat-file CMS that runs without a database.