Cross-Browser Identification

Identify the same user across Chrome, Firefox, Safari, and Edge on the same device.

How It Works

The crossBrowserId uses only hardware-level signals that don't change between browsers. All values are normalized to absorb browser-specific differences:

• GPU vendor and renderer — ANGLE wrapper strings are stripped to extract the real chip name (e.g. ANGLE (Apple, ANGLE Metal Renderer: Apple M4, ...) → Apple M4)
• CPU math precision — rounded to 8 significant digits to absorb V8 vs JavaScriptCore floating-point diffs
• Screen resolution and DPR — colorDepth/pixelDepth excluded (Chrome reports 30, Safari reports 24 on the same display)
• Timezone and locale — locale normalized to base language (pl-PL → pl)
• Installed fonts (OS-level)
• Audio sample rate (hardware-dependent)
• Local TTS voice languages — unique language set only, not voice names/count (Chrome exposes more voices than Safari)
• Touch point capability

Usage

import neoprint from '@neoprintjs/core'

const fp = await neoprint.get()
console.log(fp.crossBrowserId) // Same on Chrome, Firefox, Safari

// Send to your server to link browser profiles
await fetch('/api/link-device', {
  method: 'POST',
  body: JSON.stringify({ crossBrowserId: fp.crossBrowserId })
})

Accuracy Considerations

Cross-browser ID is medium collision resistance — it's possible for two different devices with identical hardware to produce the same ID. Best used as one factor in a multi-signal identification system.

Signals that help differentiation:

• Different GPU models → different renderer strings
• Different font sets installed
• Different TTS voice language sets
• Different CPU architectures (Math precision)

Signals excluded (differ per browser on the same device):

• User-Agent, plugins, extensions
• Canvas rendering (engine-dependent)
• WebGL extensions (browser-dependent)
• Storage quotas, permissions
• hardwareConcurrency (Safari caps to 8 on high-core CPUs)
• deviceMemory (Safari doesn't expose this API)
• colorDepth / pixelDepth (Chrome reports 30-bit, Safari reports 24-bit)
• Locale format (pl vs pl-PL)
• TTS voice names/count (Chrome exposes more than Safari)