Real Time Collaborative SaaS Architecture: CRDTs, WebSockets & Local First Canvas State Management

Traditional client server synchronization relies on pessimistic database locks or Operational Transformation (OT) servers that serialize every keystroke. This introduces intolerable latency over variable internet connections. By adopting CRDTs (such as Yjs or Automerge), client state is represented as a mathematically provable convergent graph. Each user edits their local state buffer with 0ms latency, while lightweight binary delta updates stream asynchronously across the peer network, converging deterministically without server side arbitration.

Managing tens of thousands of persistent full duplex WebSocket connections requires decoupled gateway architectures. We deploy stateless edge WebSocket proxies on regional edge nodes, backed by distributed Redis Pub/Sub clusters or Cloudflare Durable Objects. Connection state, presence heartbeats, and room memberships are isolated so that node redeployments never terminate active multiplayer sessions.

Multiplayer interactions require high frequency updates (live cursor positions, viewport scrolling, selection bounding boxes) that should never touch database storage. We bifurcate communication into two distinct channels: an ephemeral presence channel transmitting 60 FPS cursor deltas over raw WebSockets, and a durable document channel synchronizing atomic CRDT document mutations.

Continuous collaborative editing produces millions of micro mutations that can bloat client memory. We implement automated periodic snapshot compaction: a headless background worker evaluates document updates, compresses historical changes into a binary blob, and writes atomic snapshot states to PostgreSQL and S3. This provides instantaneous document loading for new users while retaining time travel audit history.