WebTransport Inspector

Debug MoQT right in your browser's DevTools. Monitor WebTransport connections, decode control messages, track subscriptions, inspect streams and datagrams, detect CMAF/fMP4/CBOR payloads, and export traces — available for Chrome and Firefox.

Install for Chrome Install for Firefox Read the docs

Browser-native MoQT debugging

Everything you need to understand MoQT traffic in your web application, built into your browser's DevTools.

Live WebTransport connections

Monitor all WebTransport connections on the page, including inside iframes. See real-time bitrate per connection, connection lifecycle events, and mid-session detection when DevTools opens late.

Control message decoding

Automatically decode MoQT control messages — setup, subscriptions, publishes, fetches, and goaways. See parsed fields alongside raw bytes with full reassembly across chunk boundaries.

Track subscription tracking

Dedicated Tracks tab shows every MoQT subscription with per-track timing, status, namespace grouping, and direction filters. Filter by active/pending, TX/RX, or group by namespace.

Stream & datagram inspector

Inspect QUIC streams and WebTransport datagrams with live byte counts, virtual-scrolled lists, text filtering, and a footer bar showing transfer totals. Pause recording or clear data on demand.

Media-aware payload inspection

Auto-detect JSON, CBOR, MessagePack, and ISO BMFF (CMAF/LOC/fMP4) payloads. Hex viewer shows inline object boundary banners with media info and per-object navigation.

Trace export & import

Export sessions as .moqtrace files for offline analysis or sharing. Import traces from colleagues or from the moqtap CLI.

Browser extension vs CLI

WebTransport Inspector

  • WebTransport connections in Chrome & Firefox (including iframes)
  • Track subscriptions, streams, and datagrams
  • ISO BMFF, CBOR, MessagePack, and JSON detection
  • Trace export compatible with the CLI

moqtap CLI

  • Native QUIC + WebTransport
  • Full QUIC transport stats
  • Active subscribe, fetch, and discovery
  • Transparent intercept proxy mode
  • Degrades the network on purpose

Related use cases

Debug MoQT sessions

See inside the protocol when building MoQT-powered web applications.

Frequently asked questions

What is the WebTransport Inspector?
The WebTransport Inspector is a free browser extension for Chrome and Firefox that lets you inspect MoQT connections running over WebTransport directly in your browser. It decodes control messages, tracks subscriptions, monitors streams and datagrams, detects media formats (CMAF/LOC/fMP4/CBOR/MessagePack), and exports traces — without leaving DevTools.
Does it work with any MoQT implementation?
Yes. The WebTransport Inspector works with any WebTransport-based MoQT implementation. It intercepts WebTransport connections at the browser level and decodes MoQT messages regardless of the library or framework used.
Is the browser extension free?
Yes, the WebTransport Inspector is completely free. It's designed to complement the moqtap CLI — use the extension for quick in-browser debugging and the CLI for deeper analysis with native QUIC support.
Does it support native QUIC connections?
No. The browser extension only sees WebTransport connections (which run over HTTP/3 and QUIC). For native QUIC debugging, use the moqtap CLI, which connects directly using the quinn QUIC implementation.
Can I use it alongside the moqtap CLI?
Yes. Both tools export and import the same .moqtrace file format. You can capture a trace in the browser extension and open it in the CLI for deeper analysis, or vice versa.
What browsers are supported?
The WebTransport Inspector is available for Chrome (and Chromium-based browsers) and Firefox. It works in any browser that supports the WebTransport API.

Debug MoQT in your browser

The WebTransport Inspector is free. For native QUIC and transparent proxy mode, the moqtap CLI covers the same protocol from the terminal.

About the CLI