Realtime · Collab2025

Realtime Whiteboard

Cross-platform collaborative whiteboard with sub-100ms latency, live cursors, chat, and operational transformation.

Role: Full-stack engineer
Timeline: 2025
Stack: Node.jsTypeScriptSocket.IOMongoDBRedis Pub/SubJWTFlutterProviderCustomPaintHiveDio

01

Screens & Architecture

Live cursors — Screen 01 · Live cursors

Chat panel — Screen 02 · Chat panel

02

The Problem

Cross-platform collaborative whiteboard with sub-100ms latency, live cursors, chat, and operational transformation.

03

How I built it

Socket.IO + Redis Pub/Sub for horizontal scaling.
Operational Transformation for conflict-free editing.
Infinite canvas with pan, zoom, and scale.
Offline support with automatic sync.

04

Outcome

50+ concurrent users per board with sub-100ms latency.
One codebase across web, Android, iOS, and desktop.