What the test showed
Onyimadu ran AdBlock Tester twice in Chrome with no ad or tracker blocker. His only extensions were Google Docs Offline and Loom. The first run scored 41/100. He then cleared the cache, because the tester warns that a page refresh can show stale results, and the second run scored 46.
The headline score matters less than the five tracker checks, which failed in both runs. Three are analytics services, including Google Analytics and Hotjar. Two are error-monitoring services, such as Sentry. Four failed outright and one was marked "most likely failed." A "failed" result means the script was not stopped.
The author's setups compared like this:
| Setup | Score | Tracker checks stopped (of 5) |
|---|---|---|
| Chrome, no blocker | 46 | 0 |
| Chrome + uBlock Origin Lite | 91 | 4 |
| Brave, default settings | 96 | 5 |
He stresses that this is not a leaderboard. Browsers differ in more than their blockers.
Why the five-point jump doesn't mean much
Only one check changed between the runs. A banner ad unit moved from "most likely failed" to "passed." The author couldn't tell whether the cache or the ad slot caused it. Don't read the 41-to-46 change as Chrome improving.
What the test can and can't tell you
The tester's own page shows its limits. I'm relying on the tester's published page text here, not on any run of my own.
- Contextual ads are unreliable. The page says ad providers block the tester's site, so that category isn't a reliable test right now.
- Banner checks are weak. The page calls them "not entirely accurate." They look only at keywords in file paths and at Flash availability. Adobe ended Flash support in December 2020, so the Flash banner check is dated.
- Load and execution are separate. The tester labels "script loading" apart from "script execution," and some results are hedged as "most likely." Loading is estimated from file size and timing. Execution checks whether the script actually ran. The author says three trackers were marked "most likely passed" on loading while their execution check failed. That is why the execution results deserve more weight.
- The tester promotes blockers. It is a site for testing ad-blocking extensions, so a score is not a full privacy audit.
The test page I can see shows version 3.1.1, dated October 23, 2024, and reports 11 services and 22 checks. It cannot confirm the author's 41, 46, 91 or 96. The author also doesn't give his Chrome build, operating system, location or settings.
What Chrome's built-in filter does
Chrome's ad filter has a narrow job. Google's help page says Chrome removes ads from sites that violate the Better Ads Standards. Examples include too many ads, flashing or auto-playing ads, and ad walls. That is a very different job from tracker blocking. An analytics script failing a test doesn't contradict what the feature is for. It does show why a quiet browser can still be a leaky one.
Google's developer documentation says Chrome identifies ad-related content by matching a filter list and analysing the JavaScript stack. The list is a condensed version of EasyList. Chrome uses this to measure ads and to intervene, for example by unloading ads that use excessive CPU or network resources. This is ad classification. It is not a promise that every tracker is stopped.
Third-party cookies: be careful with the wording
The author says Chrome lets third-party cookies through by default. The official picture is more nuanced. Google said on April 22, 2025 that it would keep its current approach of giving users a choice about third-party cookies. It also said it would not add a new standalone prompt. It noted that Incognito mode already blocks them by default.
Chrome Help describes third-party cookies as a user-selectable setting. It also warns that blocking them can break some sites. On a work- or school-managed Chromebook, you may not be able to change the setting. So "Chrome allows them by default" may hold for many standard setups, but I wouldn't claim it for every configuration. The author's claim that Safari, Firefox and Brave block them by default is his own and I haven't verified it here.
Cookie controls and script blocking are also different protections. Blocking third-party cookies doesn't stop an analytics script from running.
How to review Chrome's cookie setting on desktop
- Open Chrome and select the three-dot menu, then Settings.
- Choose Privacy and security, then Third-party cookies.
- Pick Allow or Block third-party cookies.
- If a site breaks, add it under "Sites allowed to use third-party cookies." You can also use the address-bar icon to allow cookies temporarily.
Per Google's documentation, a temporary allowance in regular browsing adds an exception for 90 days or until you turn it off. In Incognito it lasts only for that session.
The uBlock Origin Lite caveat
The author's fix for Chrome was uBlock Origin Lite. It is built for Chrome's Manifest V3 extension system, and it has real limits. Search coverage describes it as a pared-down version of uBlock Origin. Manifest V3 caps the number of filtering rules and removes the dynamic blocking that made uBlock Origin effective. TechRadar puts it more bluntly: the Lite version will still work but won't block every ad. One site that sells a rival tool, AdBlock Tester itself, warns that Chrome users accept some loss of filtering capability. Treat that as a view from an interested party.
Edge users aren't in the same position. PrivacyTools.io lists uBlock Origin Lite as available for Chrome, Edge and Safari. TechRadar reported that Edge still offered Manifest V2 support when it covered Chrome's cutoff, with no confirmed switch-off dates. I'd check Edge's current status before relying on that, because the report may be dated.
Practical takeaways
- Read the categories, not the total. The aggregate score mixes strong checks with weak ones.
- Weigh script execution above load estimates. Treat "most likely" results as unresolved.
- Test your own setup. Clear the cache between runs and use a consistent browser profile. Try it with and without extensions.
- Don't stack blockers. The tester warns that running several ad blockers together can hurt how they work.
- Treat one score as an anecdote. The numbers here come from one person, with no controls and no repeat runs.
Bottom line
The lesson holds up even with the caveats. Chrome's built-in ad filter and its cookie setting are separate privacy controls from blocking tracking scripts. A quick test can show that scripts ran in your setup. It can't prove what happens on every site, so it's a starting point for deciding on a blocker. It isn't a privacy audit.