WebTransport Inspector — moqtap

Inspect WebTransport connections and MoQT protocol traffic right from Chrome DevTools.

moqtap adds a new panel to DevTools that gives you full visibility into WebTransport sessions — whether you're debugging a media pipeline or working on MoQT protocol implementations.

What it does:

• Captures all WebTransport connections on a page, including those created inside Web Workers (essential for WebCodecs and MediaSession workflows)
• Auto-detects the MoQT protocol and draft version directly from wire bytes — no configuration needed
• Decodes MoQT control messages with full field display, so you can see subscribe requests, track info, and errors as they happen
• Tracks active subscriptions with namespace and track name resolution
• Shows live bitrate for each session, so you can monitor throughput at a glance
• Includes a stream data viewer with hex and JSON modes for inspecting raw payloads
• Detects content types automatically — fMP4 video segments, JSON control data, and raw binary
• Adds filtering and grouping tools for tracks and streams, including namespace grouping, active-only view, and TX/RX direction filters
• Lets you pause stream payload recording without losing control messages or track lifecycle visibility
• Captures stack traces for outgoing control messages and unidirectional stream creation, with clickable source links in DevTools
• Lets you export and import .moqtrace files to share debug sessions with your team

Works with:

• MoQT drafts 07 through 17 (auto-detected)
• Plain WebTransport connections (non-MoQT) are displayed gracefully
• WebTransport in Web Workers and SharedWorkers
• High-throughput video streaming sessions (tested at 40+ Mbps)

Built for developers working with WebTransport and Media over QUIC Transport. Lightweight, non-intrusive, and designed to stay out of your way on sites that don't use WebTransport.

Open source: https://github.com/moqtap/extension