How Figma Rebuilt Its Multiplayer Engine for 500 Users per File

Episode notes

Figma's multiplayer engine lets hundreds of designers edit the same file simultaneously. How did they rebuild it from scratch to handle over 500 concurrent users per document without conflicts or lag? Lucas and Luna break down the architecture: the shift from CRDTs to a custom conflict-resolution layer, the 'change tree' data structure that replaced operational transforms, and the decision to move from WebSockets to WebRTC data channels for sub-200ms sync. They also discuss the engineering trade-offs: why Figma chose JavaScript over Rust for the client, how they handle undo/redo in a multi-user environment, and the surprising bottleneck that was the browser's own garbage collector. A concrete look at real-time collaboration at scale. #Figma #MultiplayerEngine #RealTimeCollaboration #CRDT #OperationalTransform #WebRTC #ConflictResolution #JavaScript #BrowserPerformance #GarbageCollection #UndoRedo #ChangeTree #Engineering #Architecture #TechLeadership #BusinessAndTechnology #FexingoBusiness #BusinessPodcast Keep every episode free: buymeacoffee.com/fexingo

• How Airbnb Rebuilt Search for 8 Million Listings42 / 100
• How GitLab Built a Single Codebase for One Million CI Pipelines45 / 100
• How Slack Rebuilt Its Search Index for 10 Million Daily Queries37 / 100
• How Notion Rebuilt Its Sync Engine for Offline-First
• How Notion Rebuilt Its Block Engine for Hybrid Local-Sync