I use many addons and extensions in my browsers some of it is for ad blocking, taking screen shots and VPNs. This question came to my mind while using free VPN addons. I usually uses VPN addons for watching videos which are IP blocked but switch offs ( in the image down right side on/off toggle button ) while using banking transactions, emailing and other personal and secure tasks.

enter image description here

I know that while switching on VPN; those companies monitor our browsing history and possibly save it in some databases. If we switch off our VPN will it still log our browsing history and send it to their databases. Can other installed add ons see/send user browsing history without their consent? Is their a add on/ extension which can monitor the behaviour of other add ons similar to firewalls in desktops?

  • Monitoring is easy for low-level interface, not high level as in "Addon monitor addon".
    – mootmoot
    Commented May 31, 2017 at 8:57

1 Answer 1


As soon as you install an add-on in your browser, you assume it to be fair. If you do not, you should not install it at first.

Using a free add-on without carefully analizing what it does, how it does it, and why the developper gives it for free is not really different that asking an unkown guy in the street to protect your house from (other) thieves and give him the keys. It may or not be efficient...

Now for the technical part. An add-on can be activated/de-activated at 2 possible levels: in the configuration options of the browser, or in its own configuration page (what is shown in question). When it is de-activated at the browser level, all is (well should be...(*)) fine: the browser does not call the add-on, so it cannot do anything; But when it is de-activated in its own configuration, it is still called by the browser so it can still monitor all the activity.

If an add-on is really malicious you cannot be totally sure of what exists in the system once it has be used once, even if you deactivate or even remove it. It has got the possibility to execute arbitrary code at user level. It should not have be able to process tasks requiring administrative priviledges (assuming you to not browse internet with an admin account), but could have changed user profile to run tasks at login. No decent plugin should do that, but if you have installed many plugins one could not be decent...

One security rules says:

If an evil guy could persuade you to run his code on your machine, it is no longer (only) your machine.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .