Your browser’s primary goal is to serve you web resources, and most browsers do this extremely well. Privacy is a different question. You may assume that since your browser has never bothered you with junk ads, clutter, or pop-ups, no one is keeping tabs.

After a free online test that takes just a few seconds, you may have a rude awakening. I ran this test on Chrome, which I use a lot, and I suggest you do the same before building confidence in your browser.

The score: 0 out of 5

The five tracker checks went the same way both times

The test in question is AdBlock Tester, and I ran it twice in Chrome. On the first run, Chrome scored 41/100. I then cleared my cache since the tester states cached results may linger. I ran it again afterward. This time the browser scored 46.

However, the overall score isn’t as useful as the five tracker checks.

A failed result means the blocker didn’t stop the script from running. Tools like Google Analytics and Hotjar are included in the analytics group. They count your visits and can keep tabs on where you click and scroll. Services like Sentry fall under error monitoring, which acts as a crash log that records details about your device.

None of these five services were stopped the two times I tested. The one marked “most likely failed” got that label simply because not all of its sub-checks were successful. So, for the results, we can assume I had four confirmed and one probable.

There are 12 other checks covering ads and banner images, and these returned problems of their own. I had a plain setup that included just Google Docs Offline and Loom extensions enabled, and there were no extensions to block ads or trackers.

Chrome’s actual job

It filters nasty ads, not nosy scripts

Any time a page loads, you end up seeing just part of what arrives. But several things load alongside, including scripts from other companies, many of which set cookies that spot you when you next visit a site using the same service. If you’ve looked at a pair of sneakers you like and end up seeing them in every sidebar, that’s most likely what happened.

The built-in ad filter on Chrome doesn’t stop this. It’s active just on sites that have been flagged as breaking the Better Ads Standards (industry guidelines for identifying intrusive ad formats). Even if a site is full of trackers, Chrome doesn’t spot it if it hasn’t broken these standards.

Third-party cookies still get through by default on Chrome. These are blocked by default in Safari, Firefox and Brave. This is a bigger surprise because, after years of planning to phase them out, Google confirmed in April 2025 that it would keep them. It then retired several of the replacement technologies it had been building by October of the same year.

So figuratively, Chrome’s filter removes the loudest guest but keeps the one who may be taking notes in the corner. Considering that Google runs one of the biggest ad businesses on the web, it’s not shocking that the company hasn’t made tracker blocking a built-in priority.

41 became 46

Five points appeared after I cleared my cache

After clearing the cache, the test score grew by five points, which sounds like some progress. But the only change was an ad unit that went from “most likely failed” to “passed.”

Only one check changed between the two runs, so this isn’t much progress. In the first run, the test couldn’t determine whether the ad slot contained an ad or was empty. It had no way to tell whether an ad was showing or just an empty block. I simply had no way of telling if it was the cache or the ad slot itself that caused the change.

I can’t put much weight on the ad results. Some ad providers can block the tester service’s website, skewing what it can detect. The banner checks look for files called “ads_banner” in SWF, GIF, and PNG formats, based on file-path keywords and Flash availability; these checks are not very convincing. The SWF format is especially dated, since Adobe ended Flash support in December 2020.

The test service uses file size and the time taken to load to estimate whether resources are blocked. There were three occasions where a tracker was marked as “most likely passed,” but its separate execution check failed.

The execution check deserves more attention. It checks whether a script actually ran instead of estimating from the resource load. The tester also recommends a specific ad blocker, so I’m wary of its overall verdict.

Chrome’s go-to ad blocker is gone, but you still have options

Chrome’s uBlock Origin extension has been phased out, but there’s still the uBlock Origin Lite extension. I did some comparisons, running the same test on Chrome with uBlock Origin Lite installed, and on Brave, which happens to be one of my favorite privacy browsers.

This table isn’t exactly a leaderboard; browsers may differ in more than their blockers. If I’m going to keep using Chrome, I’d have to keep uBlock Origin Lite enabled.

This test revealed that my browser wasn’t protecting my privacy as much as I thought.