You can install the Sentinel Chrome extension directly from your browser's add-on store:
| Blocklist | DNR Ruleset | Description |
|---|---|---|
| Easylist | advert-dnr |
This ruleset blocks ads and trackers. |
| Easyprivacy | tracker-dnr |
This ruleset blocks tracking scripts. |
| Fanboy's Social Blocking List | social-dnr |
This ruleset blocks social media trackers. |
| Test Site / API | Canvas Fingerprint | Audio Fingerprint | WebGL Fingerprint |
|---|---|---|---|
| browserleaks.com/canvas | ✅ Different | — | — |
| webbrowsertools.com/canvas-fingerprint | ✅ Different | — | — |
| webbrowsertools.com/audiocontext-fingerprint | — | ✅ Different / Unstable | — |
| audiofingerprint.openwpm.com | — | ✅ Different | — |
| webbrowsertools.com/webgl-fingerprint | — | — | ✅ Different |
| browserleaks.com/webgl | — | — | ✅ Different |
Legend:
✅ Different — The fingerprint changes on each reload or is randomized
— Not tested / Not applicable
This matrix summarizes Sentinel's effectiveness at defeating fingerprinting on major test sites for each API.
Sentinel protects against canvas fingerprinting by intercepting and modifying the results of canvas API calls that are commonly used for browser fingerprinting. When fingerprinting protection is enabled, Sentinel injects a content script into every page and all same-origin iframes. This script overrides key canvas methods (getImageData, toDataURL, and toBlob) in both the main window and any accessible iframes.
Whenever a website or script tries to read pixel data from a canvas (for example, to generate a unique fingerprint), Sentinel's overrides add subtle, random noise to the pixel data. This ensures that the fingerprint generated from the canvas will be different each time, making it unreliable for tracking users.
The extension also monitors for dynamically created iframes and patches their canvas prototypes as soon as they are accessible. This approach defeats advanced fingerprinting techniques that attempt to bypass protections by creating canvases inside iframes.
https://browserleaks.com/canvas Different fingerprint each time. https://webbrowsertools.com/canvas-fingerprint/ Different fingerprint each time.
Sentinel protects against audio fingerprinting by intercepting and modifying the results of key Web Audio API methods that are commonly used for browser fingerprinting. When fingerprinting protection is enabled, Sentinel injects a content script into every page and all same-origin iframes. This script overrides important Web Audio methods such as AnalyserNode.getFloatFrequencyData, AudioBuffer.getChannelData, and OfflineAudioContext.startRendering.
Whenever a website or script tries to read audio data for fingerprinting, Sentinel's overrides add subtle, random noise to the audio data. This ensures that the fingerprint generated from the audio context will be different each time, making it unreliable for tracking users.
The extension is careful to only add a very small amount of noise, so that legitimate audio playback and processing are not noticeably affected, but fingerprinting scripts cannot get a stable, unique value.
- https://webbrowsertools.com/audiocontext-fingerprint/ — Breaks fingerprinting (shows indefinite loading or inconsistent results).
- https://audiofingerprint.openwpm.com/ — Different fingerprint each time.
Sentinel protects against WebGL fingerprinting by intercepting and modifying the results of key WebGL API methods that are commonly used for browser fingerprinting. When fingerprinting protection is enabled, Sentinel injects a content script into every page and all same-origin iframes. This script overrides important WebGL methods such as getParameter, getExtension, and readPixels.
- https://webbrowsertools.com/webgl-fingerprint/ — Different fingerprint each time.
- https://browserleaks.com/webgl — Different fingerprint each time.
While testing Sentinel in Firefox, you may see errors like:
Firefox does not allow Declarative Net Request (DNR) rules to redirect network requests to data: URLs (such as base64-encoded video or JavaScript). This is a browser security restriction. Chrome allows some data: URL redirects, but Firefox blocks them entirely.
To ensure compatibility with Firefox, I replaced all DNR rules that redirected to data: URLs with rules that simply block the request instead. This avoids the error and maintains effective blocking of unwanted resources.
Summary:
- These errors are Firefox-specific and caused by its restriction on
data:URL redirects in DNR rules. - The solution is to use
"block"actions instead of"redirect"todata:URLs for maximum compatibility.