AppFlowy
An open collaborative workspace with rich documents, databases, boards, calendars, local-first apps, and optional cloud or self-hosted sync.
Why use it
AppFlowy lets teams place GDDs, research, asset inventories, and tasks in one structure while retaining more deployment choice than pure SaaS.
Where it fits
Use prototypes and playtests to find core experience problems while they are still cheap to fix.
What to check
Real-time collaboration and clients evolve quickly, so test deployment and sync; assess AGPL and commercial licensing for how you distribute or modify it.