Media Codec & MIME Type Fingerprint

Test which audio and video codecs your browser supports. Codec support varies significantly across browsers and devices, making it a useful fingerprinting vector.

Data stored in window.fingerprint.codecs
What are Media Codecs?

Media codecs compress and decompress audio/video data. Support varies by browser, OS, and hardware. Trackers use codec combinations to identify devices—especially AV1, HEVC, and Opus support which indicates newer hardware.

Summary & Global Hash

Codec support overview and combined fingerprint
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Video Codecs
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Audio Codecs
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API Tests

Global Fingerprint

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Combined hash of all codec support

Video Codecs

Supported video compression formats
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Audio Codecs

Supported audio compression formats
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Codec API Support Matrix Computing...

Comprehensive codec support across HTMLMediaElement, MediaSource, and MediaRecorder APIs
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How Codec Fingerprinting Works

Why Codec Support Matters for Tracking

Different browsers, operating systems, and hardware support different codec combinations. For example:

  • AV1 support indicates a newer browser or recent OS update
  • HEVC (H.265) is supported on Apple devices but rarely on Windows/Linux
  • Opus is supported on Firefox/Chrome but not older browsers
  • FLAC support varies significantly across platforms

By testing dozens of codec combinations, trackers can narrow down your exact browser, OS version, and sometimes even hardware model.

Entropy Analysis

Codec fingerprinting provides moderate entropy (4-8 bits typically). While not as unique as Canvas or WebGL, it's still valuable because:

  • It's extremely stable—codec support doesn't change unless you update your browser/OS
  • It's difficult to spoof without breaking media playback
  • It correlates with other signals (OS, hardware, browser version)
  • Testing is fast and doesn't require user permission
Protection Methods

Codec fingerprinting is difficult to prevent because:

  • Blocking codec detection breaks video/audio playback
  • Spoofing codec support can cause media errors
  • Privacy browsers (Tor, Brave) normalize codec support, but this may reduce functionality

Best practices: Use privacy-focused browsers with fingerprint resistance, keep software updated to match common configurations, and avoid browser extensions that add unusual codec support.