Cloudflare Realtime SFU Reference
Expert guidance for building real-time audio/video/data applications using Cloudflare Realtime SFU (Selective Forwarding Unit).
Reading Order
| Task | Files | ~Tokens |
|---|---|---|
| New project | README → configuration | ~1200 |
| Implement publish/subscribe | README → api | ~1600 |
| Add PartyTracks | patterns (PartyTracks section) | ~800 |
| Build presence system | patterns (DO section) | ~800 |
| Debug connection issues | gotchas | ~700 |
| Scale to millions | patterns (Cascading section) | ~600 |
| Add simulcast | patterns (Advanced section) | ~500 |
| Configure TURN | configuration (TURN section) | ~400 |
In This Reference
- configuration.md - Setup, deployment, environment variables, Wrangler config
- api.md - Sessions, tracks, endpoints, request/response patterns
- patterns.md - Architecture patterns, use cases, integration examples
- gotchas.md - Common issues, debugging, performance, security
Quick Start
Cloudflare Realtime SFU: WebRTC infrastructure on global network (310+ cities). Anycast routing, no regional constraints, pub/sub model.
Core concepts:
- Sessions: WebRTC PeerConnection to Cloudflare edge
- Tracks: Audio/video/data channels you publish or subscribe to
- No rooms: Build presence layer yourself via track sharing (see patterns.md)
Mental model: Your client establishes one WebRTC session, publishes tracks (audio/video), shares track IDs via your backend, others subscribe to your tracks using track IDs + your session ID.
Choose Your Approach
| Approach | When to Use | Complexity |
|---|---|---|
| PartyTracks | Production apps with device switching, React | Low - Observable-based, handles reconnections |
| Raw API | Custom requirements, non-browser, learning | Medium - Full control, manual WebRTC lifecycle |
| RealtimeKit | End-to-end SDK with UI components | Lowest - Managed state, React hooks |
Recommendation: Start with PartyTracks for most production applications. See patterns.md for PartyTracks examples.
SFU vs RealtimeKit
- Realtime SFU: WebRTC infrastructure (this reference). Build your own signaling, presence, UI.
- RealtimeKit: SDK layer on top of SFU. Includes React hooks, state management, UI components. Part of Cloudflare AI platform.
Use SFU directly when you need custom signaling or non-React framework. Use RealtimeKit for faster development with React.
Setup
Dashboard: https://dash.cloudflare.com/?to=/:account/calls
Get CALLS_APP_ID and CALLS_APP_SECRET from dashboard, then see configuration.md for deployment.