'Twenty - The #1 Open-Source CRM'
Twenty is an Open Source Customer Relationship Management system.
Twenty has a Data Model Visualization:

Twenty features relational data mapping to custom fields
Twenty uses GitHub to publicly manage product workflow:
!Screenshot 2025 02 18 at 3.57.53 PM_Twenty__Roadmap.png!Screenshot 2025 02 18 at 3.58.12 PM_Twenty__Kanban on GitHub.png
Twenty uses GitHub as a Content Management Systems
Twenty posts it's Documentation using GitHub as a repository for it's Markdown content.
!Screenshot 2025 02 18 at 1.37.12 PM_Twenty__GitHub as CMS.png