Tech Stack
React
Typescript
Node.js
Socket.io
Redis
PostgreSQL
Description
SyncPad is a Google-Docs-style collaborative editor built to learn distributed-systems tradeoffs hands-on. Document state is a Yjs CRDT synced over WebSockets, so concurrent edits merge without a central lock.
Presence (cursors, selections, avatars) rides a separate ephemeral channel via Redis pub/sub, and documents persist as periodic CRDT snapshots plus an operation log in Postgres.
- Handled 50+ concurrent editors on a single document in load tests with sub-100ms edit propagation.
- Implemented offline-first editing: local changes queue in IndexedDB and merge cleanly on reconnect.
- Built live cursors and presence over Redis pub/sub, isolated from document traffic.
- Snapshot + oplog persistence enables full document history and point-in-time restore.
Page Info
Editor Surface
Minimal writing surface with live remote cursors, presence avatars, and inline commenting.
Export & Sharing
One-click export to markdown/docx and shareable read-only links.
