Trace Export & Import

The .moqtrace format

All moqtap tools share the .moqtrace file format — a binary format using CBOR encoding. It’s compact, streamable, and readable by any language with a CBOR library. The file starts with an 8-byte MOQTRACE magic header, followed by session metadata and a sequence of CBOR-encoded events.

Each event includes:

• Timestamp (microseconds)
• Direction
• Parsed message fields
• Raw bytes (for re-parsing)
• Parse warnings (if any)

Recording traces

CLI

# Record intercept session to a .moqtrace file
moqtap intercept -u moqt://relay.example.com -o session.moqtrace

Desktop app

Click Export Trace during or after a session to save a .moqtrace file containing every event.

Browser extension

Click the export button in the DevTools panel to save the current session as a .moqtrace file.

Replaying traces

CLI

# Replay a trace with text output
moqtap trace session.moqtrace

# JSON output
moqtap trace session.moqtrace --format json

# Hex dump mode
moqtap trace session.moqtrace --hex

Desktop app

Open a .moqtrace file via File > Open Trace. moqtap loads the entire timeline and switches to log analysis mode:

• Full timeline scrubbing (forward/backward)
• Search and filter across all events
• No live interaction (read-only)
• Latency displayed relative to first event

Browser extension

Import previously saved traces back into the extension for review in the DevTools panel.

Sharing traces

.moqtrace files are self-contained — share them via email, Slack, or attach them to GitHub issues for bug reports. Traces captured in one moqtap tool can be opened in any other.

Detail levels

The @moqtap/trace library supports configurable detail levels:

Level	What’s captured
Control only	Control messages, no data stream content
Headers	Control messages + data stream headers
Headers + sizes	Headers with payload sizes but no payload data
Headers + data	Headers with full payload data
Full	Everything including raw wire bytes