Productivity
Collaborative Whiteboard with AI Clustering
Brainstorm on a shared canvas and let AI group sticky notes into themes
Advanced26h2–4
tldrawYjsEmbeddings
17/20Local-First Notes with Peer Sync
Notes that work offline and sync between your devices without a central server.
Advanced28h1–3 people15/20 fit
Build Local-First Notes with Peer Sync for privacy-minded note takers in ~28h with 1–3 people. Stack: Yjs + IndexedDB + WebRTC.
Why it wins: Demonstrates serious engineering with a clean demo.
Build flow
01 · Problem
Cloud notes break offline and put all your data on someone else's server.
02 · Solution
Store notes in a CRDT with Yjs, persist locally and sync peer-to-peer or via a tiny relay, with conflict-free merges.
03 · Build
- 1Model notes with Yjs
- 2Persist to IndexedDB
- 3Add WebRTC sync
- 4Show history
04 · Demo
Edit the same note on two laptops offline and watch them merge.
MVP checklist
- Offline editing
- Peer sync
- Conflict-free merges
- Version history
Tech stack
| Tech | Role | |
|---|---|---|
| Yjs | CRDT realtime sync | Backend |
| IndexedDB | Tooling | Tool |
| WebRTC | Tooling | Tool |
Reference repos
Open-source projects you can build on. Links checked 2026-10-31.
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