178 reviews
  • Could do with the notification not encroaching on the real estate, but rather as a traditional notification which disappears.
    I understand why it was done this way (so that the site can be white-listed etc) but that's better accomplished by a toolbar button for those that want it.
    This si functionally much better than the other implementation only slightly marred.
    Since version 0.4.0 the notifications are different and use much less space.
  • Google is already able to identify your canvas as spoofed. Try to sign up for a Gmail account and you will see. Soon every tracking script online will be able too. An update is needed urgently!
    I always get to do the phone verification regardless of the addon.
  • The best canvas blocker I've tried.
  • The only thing I miss that fingerprint should not change within the same session, since two tries can easily reveal faking.
    Author mentioned that will take care of that too.
    Otherwise very very good job.
    Thank you
  • Great addon!

    It would be nice if there would be an option to automatically "whitelist" all sites on the Firefox cookie whitelist also :-)
  • Works with my most current version of FF and is compatible with all addons. A+
  • version 0.1.6 does not work with Mozilla 28.0
    please make a support for older versions
    Please file your issue/support request at https://github.com/kkapsner/CanvasBlocker/issues
  • thank you for your work! :)
  • Works better than expected, love it, finally no more tracking.
  • Works perfectly, does what it says! Rate this addon guys, there is no alternative to this one! Tested on panopticlick.org.

    Funktioniert wunderbar, alles zu vollster Zufriedenheit! Bewertet, damit sich das herumspricht! Getestet auf panopticlick.org.

    Funciona perfectamente. iDen cinco estrellas para que se sepa! Comprueben antes pero ahora mismo funciona muy bien en la pagina del eff.
  • Top notch, does what it says and solves the problem so that we no longer need disable Canvas. Extension needs more exposure, cannot believe I only just found it today.
  • great addon for mozilla browser
    PaleMoon has this feature implemented
    go to about:config and set "canvas.poisondata" to true. That's it!
  • Works great and blocks everything, running on Cyberfox 43.
  • Works well to block canvas fingerprinting.
    Unfortunately, I have to turn when reading PDFs. It doesn't really work with Firefox's PDF.js reader. It asks for permission every time I scroll to a new page.
    Also, I would like buttons to easily whitelist/blacklist a site without having to go into the options every time I want to do that.
    You might consider using the "ask only once" option or the faking mode. Latter has a nice notification system with some buttons and it is the main focus of the current development.
  • excellent countermeasure, validated on https://www.browserleaks.com/ and http://amiunique.org

    Hi kkapsner. Thanks. Version 0.1.3 indeed works on FF28. Maybe a FF bug caused it to offer updating to v0.2 after updating to FF28. Right now it only offers updating to 0.1.6, which is the latest that indicates (incorrectly?) FF28 as supported.

    And thanks for the extension! Now I just need something to block/control CSS transitions... :)

    And also thanks for pointing out, indirectly, that it's possible to download older versions from the Mozilla site :) (hidden at the bottom on the page, under the misleading title "Version Information", then "See complete version history". There's also more info there on supported FF versions per extension version).

    I'll use Github in the future (*sigh* another something that needs an account...).


    I'm on FF v28. The extension carried over from a previous FF version, and I also updated it after moving to v28. In FF's settings it's not disabled due to being "incompatible". Yet, in the FF addons site it says it's incompatible with v28.

    Assuming it's supposed to just block Canvas elements (which is what I'm after; fingerprinting is a secondary concern which I wasn't aware of before), I don't see any blocking action. The same was true also with the previous FF version I was using: no blocking. I was able to install it to begin with, so I think it should have worked, but maybe I'm missing something.
    Version 0.2.0 is definately not working with FF 28. Try an older version (I would start with 0.1.6 and then go backwards). If you realy want to have blocking of the canvas you have to set the blocking mode to "block all".

    PS: If you have further problems and want to contact me, please use github: https://github.com/kkapsner/CanvasBlocker/issues .
  • You answered: "The addon does not report based on URL but on the JavaScript that is executed on the site."

    So I have a suggestion: This behaviour "accuse" almost every Url / Website, to spy via Canvas-technic.
    Can you reduce this warning to only sites, where that Canvas-technic is really used?
    I would say that differentiating between fingerprinting and legitimate use of the readout API is impossible without a full static code analysis which would make your browser incredible slow - especially while looking at PDFs.

    The notification also is not meant to be an accuse but an information that a call to the readout API did not return the real values but some faked ones.

    So I'm sorry but the answer is "No".
  • Problem fixed by a development version made available by author at github.

    Raising star rating to 5.
  • Great plugin.
    Can you please update latest release for Palemoon browser ?

  • Essential addon for everybody, works great & easy to use, with fake readout api mode, it doesn't break websites.
  • Works great in Firefox. Unfortunately it's not available for Thunderbird. Hopefully that will be fixed soon!
    Thank you for your rating.

    Can you please open an issue on https://github.com/kkapsner/CanvasBlocker/issues where you explain why you need it in Thunderbird. Thank you.
  • I can't answer to my own thread, so here i have a question from the https://addons.mozilla.org/de/firefox/addon/canvasblocker/reviews/660262/ thread.
    Is the Components.utils.exportFunction realy needed? If yes, maybe you can help us: http://forum.palemoon.org/viewtopic.php?p=45352#p45352
  • Soundcloud doesn't work with this Add-on
    The site works fine with one of the "Readout-API"-modes.
    The "block all"-mode interferes with the loading icon...
  • Since there is no option to disable canvas functionality directly in the browser, this add-on is essential for everyone concerned about online privacy.

    I'm using it alongside Adblock Edge, NoScript and Self-Destructing Cookies.
  • Excellent add-on, shows all the sites that try to manipulate canvases, and stops them from doing it. You can also set a whitelist, note that some Google pages are whitelisted by default!

    One bug: this add-on causes a memory leak in Firefox 32: after browsing for a while you will see in about:memory a lot of ghost windows, which also make the browser laggy as the garbage collector repeatedly tries to clean them up. Temporarily disable this add-on (no restart required) and the GC will shortly get rid of them. This should be fixed though.
    Thank you for the Review.

    I will try to hunt down the memory leak.

    The google-Page that is white listed should be related to google-maps. But I added a note in the description.

    EDIT: in version 0.1.3 the memory leak should be gone.