TinaCMS https://tina.io

Tina is an open-source, Git-backed headless content management system (CMS) that empowers both developers and content creators to collaborate seamlessly on a single platform. Tina enables developers to craft a custom visual editing experience perfectly tailored to their website or application while supporting a broad range of content types such as Markdown, MDX, and JSON.

https://nextjs.org/

https://nextjs.org/docs/getting-started/installation

npx create-next-app@latest