This is for software development for non web technology frontend that you want to have a backend platform for.

Full UI Development Optional

Directus Framework

Links

The Open Source Headless CMS (and More)

Articles

Directus Toolmaking Help

Some UI Development Required

Strapi - Open source Node.js Headless CMS 🚀

Full UI Development Required

Supabase | The Open Source Firebase Alternative

Appwrite - Open-Source End-to-End Backend Server

PocketBase - Open Source backend in 1 file