Chrome 76: Websites now can’t detect if you’re in Incognito mode

We’ve covered Google added Filesystem API in Incognito flag to Chrome, which, when enabled, you can’t be detected by sites when you visit them in incognito mode, as per our findings, the flag is now working successfully in Chrome 75 Canary.

In Google Chrome’s incognito mode, the FileSystem API is not enabled by default, this allows websites to detect when you browse them from the incognito window and ask you to disable private mode and buy a subscription or register on their site and become a member to read their site. We’ve noticed a news site doing this consistently.

FYI, the Private or incognito mode is not anonymous browsing, but it protects your privacy to some extent and when compared with regular browsing mode, you’ll be tracked less, browsing history won’t be recorded, cookies of websites you visited during the session will be deleted once you exit.

Some news sites count your visits when you visit in regular browsing mode and asks to become a member after a certain limit, to avoid that, users visit news sites privately, but with Chrome’s flaw, you’ll be detected when you visit in incognito, now you can avoid this and soon Google will enable FileSystem API by default for incognito mode and expect them to ship with Chrome version 75 76.

Enable Filesystem API for Incognito mode in Google Chrome

1. Visit chrome://flags

2. Find the “Filesystem API in Incognito” flag

3. Select Enabled, restart the browser.

Test sites can detect you or not in incognito mode

1. Click on menu and select new incognito window

2. Visit this testing site jsfiddle.net/w49x9f1a/

3. A few days before, the above site after enabling the flag, used to show “it seems like you’re in incognito mode” message, now, it shows “it does not seem like you are in incognito mode”, no doubt, the feature is working.

We’ve also visited the news site we mentioned above in private browsing mode to check the feature is working, it is, checks that in the screenshot and video. Do note, the flag is also available in Chrome 74 beta, but hasn’t worked.

UPDATE June 11, 2019: Chrome 76 has the feature working out of the box, without need to enable “FileSystem API in Incognito” flag. Paul Irish who works on Performance team for light house and Chrome developers confirmed this on twitter.

Chrome Incognito mode has been detectable for years, due to the FileSystem API implementation. As of Chrome 76, this is fixed.
Apologies to the “detect private mode” scripts out there. 💐 pic.twitter.com/3LWFXQyy7w

— Paul Irish (@paul_irish) June 11, 2019