AudioLab: Web Audio Forensics and Tracking Analysis

Record Web Audio API calls to study audio fingerprint collection techniques and verify privacy protection.

Prerequisites

• BotBrowser installed and running. See Installation Guide.
• A profile file (.enc for production).

Quick Start

Record all Web Audio API calls to a JSONL file:

chromium-browser \
    --bot-profile="/path/to/profile.enc" \
    --bot-audio-record-file=/tmp/audiolab.jsonl \
    --user-data-dir="$(mktemp -d)" \
    "https://example.com"

After the session, /tmp/audiolab.jsonl contains every Web Audio API call the page made. Open it in the Audio Viewer  to inspect events interactively.

How It Works

When --bot-audio-record-file is set, BotBrowser intercepts every Web Audio API call at the browser engine level and writes it to a JSONL file. Each line is a JSON object representing one API call, including:

• Event type: context_create, node_create, param_set, connect, start, start_rendering, read_channel_data, analyser_read, codec_check, and more
• Full parameters: all arguments serialized (node types, parameter values, timing, sample previews)
• Audio graph topology: which nodes connect to which, showing the complete signal routing
• Data extraction: sample previews (first 10 + last 10 values), sums, frequency data, codec results
• Execution context: sequence number, timestamp, process/thread ID, source URL

Common Scenarios

Record and analyze with Playwright

import { chromium } from "playwright-core";
 
const browser = await chromium.launch({
    executablePath: process.env.BOTBROWSER_EXEC_PATH,
    headless: true,
    args: [
        `--bot-profile=${process.env.BOT_PROFILE_PATH}`,
        "--bot-audio-record-file=/tmp/audiolab.jsonl",
    ],
});
 
const page = await browser.newPage();
await page.goto("https://example.com");
// Let the page run its audio fingerprinting
await page.waitForTimeout(5000);
await browser.close();
 
// Now inspect /tmp/audiolab.jsonl

View recordings in the Audio Viewer

Open the HTML-based viewer to inspect recordings interactively:

1. Navigate to the Audio Viewer 
2. Load your .jsonl file
3. Browse events, view the audio graph topology, and inspect extracted data

Identify which fingerprinting recipe a site uses

The Audio Viewer automatically detects known recipes:

# Record a site's audio fingerprinting
chromium-browser \
    --bot-profile="/path/to/profile.enc" \
    --bot-audio-record-file=/tmp/audiolab.jsonl \
    --user-data-dir="$(mktemp -d)" \
    "https://target-site.com"
 
# Quick check: what context parameters were used?
cat /tmp/audiolab.jsonl | jq 'select(.type == "context_create")'
# The viewer auto-detects common patterns from context parameters

Inspect extracted audio data

# See what data the tracker extracted
cat /tmp/audiolab.jsonl | jq 'select(.type == "read_channel_data")'
 
# Check codec probing
cat /tmp/audiolab.jsonl | jq 'select(.type == "codec_check")'

Cross-platform protection validation

Record the same page on multiple platforms and compare the JSONL output to verify that BotBrowser’s noise produces consistent protection:

# Record on Linux host
chromium-browser \
    --bot-profile="/path/to/win-profile.enc" \
    --bot-audio-record-file=/tmp/audiolab-linux.jsonl \
    --user-data-dir="$(mktemp -d)" \
    "https://example.com"
 
# Compare with recording from macOS host
diff /tmp/audiolab-linux.jsonl /tmp/audiolab-macos.jsonl

Record audio and canvas simultaneously

chromium-browser \
    --bot-profile="/path/to/profile.enc" \
    --bot-audio-record-file=/tmp/audiolab.jsonl \
    --bot-canvas-record-file=/tmp/canvaslab.jsonl \
    --user-data-dir="$(mktemp -d)" \
    "https://example.com"

Troubleshooting / FAQ

Next Steps

• AudioLab Documentation . Complete reference including recording format, event types, and viewer usage.
• Audio Fingerprinting. Configure audio noise and rendering consistency.
• CanvasLab. Similar forensics tool for Canvas 2D, WebGL, and WebGL2.
• CLI Flags Reference. Flag documentation.

Related documentation: AudioLab Tool  | CLI Flags: —bot-audio-record-file

Legal Disclaimer & Terms of Use  - Responsible Use Guidelines . BotBrowser is for authorized fingerprint protection and privacy research only.