CanvasBlocker
Alters some JS APIs to prevent fingerprinting.
CanvasBlocker: Prevent Fingerprinting with Firefox Add-On
CanvasBlocker is a proactive Firefox add-on that aims to significantly improve your online privacy by manipulating JavaScript APIs, thus preventing intrusive fingerprinting techniques. It gives you the freedom to block these APIs completely for specific websites, or fake their fingerprint-friendly readout API, effectively altering the values obtained and ensuring a consistent fingerprinting is not possible. From 'Canvas 2D' and 'WebGL' to 'Audio' and 'History', it offers protection across many fingerprinting APIs. Users can also adjust the blocking modes according to their needs.
Add-on stats
Manifest V2
By: kkapsner
Rating: 4.61 
4 new ratings
(428)
Weekly download count: 1,756
Firefox on Android: Yes
Permissions:
- <all_urls>
- storage
- tabs
- webRequest
- webRequestBlocking
- contextualIdentities
- cookies
- privacy
Size: 459.64K
URLs: Privacy policy
Full description: See detailed description
Ranking
# 429 ▼ 2
Other platforms
Not available on Chrome
Not available on Android
Not available on Edge
User reviews
These summaries are automatically generated weekly using AI based on recent user reviews.
Firefox Browser Add-ons does not verify user reviews, so some user reviews may be inaccurate,
spammy, or outdated. Pros
- Helps stop sites and corporations from tracking internet activity.
- The extension works without major issues for most users.
- Provides significant privacy protection during browsing.
Cons
- Users face issues with captchas when using the add-on.
- Reported unique fingerprints still appear despite using the add-on.
- It does not prevent tracking in all cases, particularly with offscreen workers.
Most mentioned
- Tracking prevention effectiveness.
- Issues with captchas.
- Inconsistent results on fingerprinting tests.
User reviews
by Firefox user 18882242, 2025-03-14
by Firefox user 17855064, 2025-03-13
by Firefox user 18871435, 2025-03-09
Add-on safety
Risk impact
CanvasBlocker requires some sensitive permissions that could impact your browser and data security. Exercise caution before installing.
Risk impact analysis details
- Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
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Risk likelihood
We don't have sufficient data to confidently determine the risk likelihood of CanvasBlocker. Use it at your own risk.
Risk likelihood analysis details
- High This extension has low user count. Unpopular extensions may not be stable or safe.
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