Explore the engineering decisions behind OutSync’s sub-10ms real-time synchronization, peer-to-peer WebRTC voice pipeline, and Monaco multiplayer engine.
Building a real-time multiplayer code editor requires solving state consistency, presence visibility, and voice communication simultaneously. OutSync achieves this by pairing a mathematical CRDT data model (Yjs) with WebSocket delta streams for text, direct WebRTC peer channels for audio, and client-side Monaco decoration matrices for remote cursor tracking.
OutSync employs Yjs state vectors and delta compression over WebSockets. Because operations commute deterministically, participants can type offline or in high-latency environments without ever creating merge conflicts.
Instead of routing heavy audio packets through expensive relay servers, OutSync establishes direct peer-to-peer WebRTC connections with DTLS-SRTP encryption, delivering sub-20ms audio with zero server recordings.
Integrated with VS Code Monaco editor core. Remote user cursors, active text selections, and line highlights are rendered via high-performance Monaco CSS decorations updated at 60 frames per second.
When code execution is triggered, payloads run in ephemeral, network-isolated Linux container sandboxes with hard memory/CPU cgroups and 5-second automatic execution timeouts.
