Recently I wanted to buy the particular product from an online website and was just searching that product during my leisure time. after some time suddenly I saw the ad of that product on Instagram and Facebook android applications. This blew away my mind because Facebook and Instagram Applications keeping track of activity I am performing on other application without my consent.

Anyone who is wise enough about privacy and security related stuff will never agree to allow other applications to track activities particular person is performing on other applications.

I have several doubts

1) How can Facebook and Instagram android application keep track of activities without any permission or privacy policy notification?

2) I know this mechanism is possible because of sharing of cookies between the apps but can only cookies are responsible for this?

3) Whether the same problem exists in the IOS as well? as IOS said to be more secure than android.

4) How secure application like banking applications restricts sharing of cookies with other applications?

5) Why there is no cookie specific permission feature available in android like we have access to give contact permission to certain apps camera permission to certain apps.


1 Answer 1


You are logged in to FB on the web browser you used to browse the shopping site, so the site operator tells FB what you were looking at. The cookies are not actually shared by anyone, FB keeps those to themselves. FB centrally determines what your account sees in the FB app, regardless of OS or device, based on everything it knows abuot you and your activities.

The solution is to block 3rd-party cookies in your web browser, a well-covered topic. You can also just sign out of FB before browsing (instead of just closing the tab), but a recent legal decision found that FB can legally track you even when you are signed out. That varies by jurisdiction, but they technically can for sure.

  • how can one use "an online website" without a browser?
    – dandavis
    Nov 14, 2018 at 17:21
  • 1
    Many of those kind of app embed a web browser, which often has cookies in common with the "browser" app on the device. There may be other ways to associate you with FB though, like if you bought something from the same store while you were signed in one day. If none of that applies, the app might be finding FB crumbs on your SD or built-in storage, or matching your IP, or somehow else matching PII with a central DB of FB logins.
    – dandavis
    Nov 14, 2018 at 17:28

You must log in to answer this question.

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