# CanvasBlocker

> Alters some JS APIs to prevent fingerprinting.

Canonical page: [https://chrome-stats.com/d/canvasblocker](https://chrome-stats.com/d/canvasblocker)

## Overview

- **ID:** `canvasblocker`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** kkapsner
- **Category:** privacy-security
- **Daily users:** 38,098
- **Weekly downloads:** 1,544
- **Rating:** 4.58 / 5 (486 ratings)
- **Version:** 1.12
- **Last updated:** 2026-02-13
- **First published:** 2014-08-04
- **Size:** 469 KB
- **Data as of:** 2026-09-07
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/canvasblocker/)
- **Privacy policy:** [https://addons.mozilla.org/firefox/addon/canvasblocker/privacy/](https://addons.mozilla.org/firefox/addon/canvasblocker/privacy/)

## Description

CanvasBlocker is a powerful Chrome extension designed to protect your privacy by altering specific JavaScript APIs that websites use to fingerprint users. It targets common fingerprinting vectors such as canvas 2D, webGL, audio, history, DOMRect, and more, allowing you to block these APIs entirely or provide fake data to avoid consistent fingerprinting.

Users can customize protection with multiple modes including blocking everything, allowing only whitelisted sites, or an optimized fake mode that balances usability and privacy. The extension also advises maintaining only one fingerprinting protection addon active to avoid performance issues. CanvasBlocker is ideal for users seeking enhanced privacy without sacrificing browsing functionality.

## Rankings

- #369 — Overall
- #23 — Privacy & Security
- #1 — prevent
- #3 — website blocker
- #6 — scan
- #6 — writer's block

## Permissions and access

### Permissions

- `<all_urls>`
- `storage`
- `tabs`
- `webRequest`
- `webRequestBlocking`
- `contextualIdentities`
- `cookies`
- `privacy`

### Content script matches

- `<all_urls>`

## Safety

- **Risk impact:** High risk impact
- **Risk likelihood:** Very low risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension has medium user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

## Review summary

CanvasBlocker is highly praised for its fingerprinting protection and privacy gains; most reviews cite its ability to change fingerprints on refresh and customizable site-specific settings that keep browsing smooth. It is generally described as lightweight and easy to test. However, a minority report inconsistent results (fingerprints not changing or fingerprint checks indicating no effect) and a few isolated complaints about site breakage on certain services. Overall, it’s viewed as a valuable privacy tool with occasional reliability caveats.

### Pros

- Changes the fingerprint on every refresh, reducing tracking.
- Strong privacy/anti-fingerprinting enhancement; widely appreciated and essential for anonymity.
- Per-site customization with adjustable strictness to prevent breakage.
- Lightweight, runs in the background and doesn't slow browsing.

### Cons

- Inconsistent effectiveness; some users report fingerprints don't change or tests show no effect.

## Similar extensions and apps

- [Canvas Blocker - Fingerprint](https://chrome-stats.com/d/canvas-blocker-fingerprint) — 17 users
- [Canvas Blocker - Fingerprint Protect](https://chrome-stats.com/d/canvas-blocker-no-fingerprint) — 419 users, 3.73 / 5
- [Canvas Fingerprint Defender](https://chrome-stats.com/d/canvas-fingerprint-defender) — 1,130 users, 3.97 / 5
- [Canvas Blocker](https://chrome-stats.com/d/canvas-blocker) — 6 users
- [Canvas Defender](https://chrome-stats.com/d/no-canvas-fingerprinting) — 2,879 users, 3.64 / 5
- [WebGL Fingerprint Defender](https://chrome-stats.com/d/webgl-fingerprint-defender) — 1,522 users, 3.56 / 5
- [WebAPI Blocker](https://chrome-stats.com/d/webapi-blocker) — 47 users, 3.50 / 5
- [Fingerprint Defender](https://chrome-stats.com/d/fingerprint-defender) — 549 users, 4.33 / 5
- [No Fingerprint](https://chrome-stats.com/d/no-fingerprint) — 1 users, 3.40 / 5
- [Fingerprint Shield](https://chrome-stats.com/d/fingerprint-shield) — 116 users, 3.13 / 5
- [block it](https://chrome-stats.com/d/block-it)
- [Precision Site Blocker](https://chrome-stats.com/d/precision-site-blocker)

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Source: [Chrome-Stats](https://chrome-stats.com/d/canvasblocker)