How to test uBlock Origin
Open the browser profile where you use uBlock Origin and confirm the extension is enabled. Its toolbar control should show that filtering is active for the test site. Then run the adblock test and wait for every network category to finish.
The result reflects all active protection, not uBlock Origin alone. A VPN, secure DNS service, or built-in browser feature can also block requests. For a useful comparison, keep those layers unchanged while you review uBlock settings.
Before you test
- Update uBlock Origin and its filter lists.
- Check that the site is not allowlisted.
- Use the browser profile you normally browse with.
- Change one setting at a time before retesting.
What uBlock Origin usually blocks
uBlock Origin uses filter lists and request context to stop known advertising, tracking, analytics, malware, and nuisance resources. Exact coverage depends on the lists enabled, their current rules, your custom filters, and the page being visited.
A strong tracker blocking result means representative requests were intercepted. It does not guarantee every tracking technique is covered. First-party analytics, server-side collection, and new endpoints may not resemble known third-party trackers.
Why the score may not be 100%
Some tested hosts may not appear in your selected lists, may be intentionally allowed to avoid breakage, or may share infrastructure with legitimate services. Another possibility is that uBlock is paused for the site or restricted by browser permissions.
A score below 100% is not automatic proof that uBlock Origin is broken. Review which categories and hosts were reachable. The adblock score guide explains why a mixed result can still represent meaningful protection.
Filter lists that affect results
Default uBlock lists cover common advertising and privacy threats. Additional maintained privacy lists can increase tracker coverage, while regional lists address local advertising patterns. List names and availability can change, so use the choices presented by your installed version rather than following an old screenshot blindly.
More lists are not always better. Overlapping rules increase complexity, and aggressive lists can break sign-in, shopping, media, or consent flows. Update the defaults first, then add only the focused coverage you need.
Cosmetic blocking versus network blocking
Network rules prevent a browser request from reaching an ad or tracker host. Cosmetic rules hide page elements such as banners, empty ad containers, or sponsored modules. The two systems solve related but different problems.
This test primarily measures whether representative resources are reachable. A page can look clean because cosmetic filtering hides an element even when a network request remains reachable. Conversely, DNS or network blocking can stop an ad while leaving a blank space.
What to check if uBlock is not working
- Confirm the extension is installed, enabled, and active for the current site.
- Open its dashboard and update filter lists.
- Review trusted-site entries and temporary allow rules.
- Check whether the browser reports permission or extension errors.
- Disable conflicting content blockers temporarily for a controlled comparison.
- Follow the broader adblock troubleshooting checklist if ads still appear.
Private window permissions can differ
Browsers commonly require explicit permission before extensions can operate in private or incognito windows. If you rely on private browsing, confirm that uBlock Origin is allowed there, open a fresh private window, and repeat the test.
Do not assume a normal-window result carries over. Private storage, cookie rules, and built-in tracking protection can change the outcome independently of the extension.
Run a fresh test
After making a focused change, close stale tabs or reload the test page and run it again. Compare the same categories and reachable hosts. A repeatable improvement is more useful than a single score that changes because several settings were altered at once.
Remember that a uBlock Origin adblock test is a diagnostic sample. Real websites use first-party ads, native promotions, video delivery, and anti-adblock code that a host probe cannot fully reproduce.
Keep a note of the lists and custom rules that produced a stable result. If coverage changes after a browser or extension update, that record helps you distinguish a permission reset from a filter-list change. It also prevents unnecessary settings from accumulating during later troubleshooting. Repeat the comparison in every browser profile you regularly use.