Strapi is an open-source headless CMS in which developers define content models and Strapi automatically generates a REST and GraphQL API for them. Editors manage content in an extensible admin panel with a Content-Type Builder, media library, roles and permissions, internationalisation and draft/publish. Strapi is written in JavaScript and TypeScript, works with SQLite, PostgreSQL, MySQL and MariaDB, and can be extended with plugins. You can host Strapi yourself or use Strapi Cloud, the vendor's managed hosting platform on which you choose a region.
The Strapi core is open source under the MIT licence; for self-hosted installations some features are only available on paid plans. When self-hosting, according to the vendor you have full control over data residency and compliance, and you can run the installation on European infrastructure. According to its privacy policy, Strapi's own systems are mainly located in the United States and the European Economic Area, and the policy also describes Strapi as a US corporation. Check this when using Strapi Cloud.