Realtime Chat System
RealtimeProductionRealtime collaborationRealtime messaging system with WebSocket channels, pub/sub presence tracking, durable message history, media uploads, and error telemetry. Use for chat products, collaborative tools, or live feeds.
Recommended for: Product teams building live messaging
Use Case
Team messaging apps, customer support chat, community platforms, collaborative tools
Best Fit Scenarios
- Support chat with persistent history
- Community channels with presence signals
- Collaborative apps with low-latency updates
Stack Breakdown
Architecture Layers
Components by Category
frontend
backend
database
infra
external
Why This Topology Works
WebSocket gateway handles persistent connections while Redis pub/sub distributes messages across server instances. Presence is kept separately from chat logic, allowing each to scale independently.
Scaling Notes
WebSocket servers scale horizontally with Redis pub/sub. MongoDB shards by room/channel. Presence state is ephemeral in Redis with TTL-based cleanup.
Observability
Track connection count, message throughput, and pub/sub lag. MongoDB slow queries on message history reads.
Typical Bottlenecks
- Frontend rendering and bundle delivery under peak traffic
- Service latency and timeout behavior on critical routes
- Write amplification and query contention on primary stores
Async Flow and Reliability
The flow is mostly synchronous. Add queue-backed workers for long-running or failure-prone operations to protect request latency.
Upgrade Path
Split high-churn domains into dedicated services, then introduce stronger queue policies and SLO-driven monitoring.
Operating Envelope
Complexity is marked as Production with an intended scope of Realtime collaboration. Use this as a planning baseline before adapting the template to your reliability and team constraints.