The Scan.now ad blocker
26,140 rules built on EasyList and EasyPrivacy, enforced by the browser itself. It never sees your traffic, it makes no network requests of its own, and it shows you what it blocked.
What it does
Built on EasyList, the list most ad blockers are built on.
Analytics, session replay, fingerprinting and social pixels, each on its own switch.
Not just how many. The panel lists the domains it stopped on the page you are on, and the ones it stops most often overall, with the list each came from.
Optional, off by default, and a stylesheet rather than a script.
The browser does the blocking. The extension is not in the request path.
What it blocks
Six lists, each with its own switch in the panel. Two come from the community projects most ad blockers are built on; four are ours, written from what we keep finding in scans. Every one is on by default.
| List | What is on it | Rules |
|---|---|---|
| EasyList | Advertising: networks, exchanges, retargeting and the servers that deliver creatives. | 13,000 |
| EasyPrivacy | Tracking: analytics, telemetry, session replay and conversion pixels. | 13,000 |
| Ads | Ad tech we added ourselves, including the exchanges that show up most in our own scans. | 66 |
| Analytics and session replay | Counting visitors, and recording what they do on the page. | 40 |
| Fingerprinting and identity | Recognising a visitor without a cookie, and the brokers that resolve identities. | 19 |
| Social pixels | Facebook, LinkedIn, TikTok, X, Pinterest, Reddit and Snap conversion trackers. | 15 |
Counts are read from the package itself, so this table cannot drift from what you download.
Why it cannot watch you
Most ad blockers work by reading every request your browser makes and deciding, one at a time, whether to let it through. That is the only way to apply a filter list in full, and it means the extension sees every address you visit. You are trusting it not to keep them.
This one cannot see them. Blocking here is declarative: the browser is handed a rule file and enforces it itself, and the extension is never in the request path. There is no callback, no listener and nothing to log. The guarantee is not that we promise to behave — it is that the architecture gives us nothing to behave badly with.
The counter works the same way. It asks the browser how many of our own rules matched, and the answer is a rule number and a time, with no address attached. The panel can still name the domains, because a rule number is looked up in the list already in the package — nothing had to watch your browsing to work that out. It all stays on your machine. The extension makes no network requests of its own, has no account and sends no analytics.
What it will not do
Every ad blocker has a line it will not cross. Most do not tell you where theirs is.
| Not done | Why |
|---|---|
| Cosmetic filtering, by default | Hiding an element by CSS selector needs code running inside every page you visit. There is an opt-in switch that adds a fixed stylesheet to collapse empty ad boxes — a stylesheet, never a script. |
| Defeating anti-ad-block detection | Blockers that fight site detection are in a running battle they lose weekly, and the breakage lands on you. |
| Every rule in the lists | Chrome guarantees an extension 30,000 enforced rules; the two lists hold over 100,000. We keep the most general — whole-domain blocks first, every exception kept. |
| First-party ads | An ad served from the same domain as the article is indistinguishable from the article to a network rule. |
| Acceptable Ads, or any paid allowlist | Some blockers take payment from advertisers to let certain ads through. There is no such list here and no arrangement with anyone. |
If you want maximum coverage, use uBlock Origin. It applies the lists in full, cosmetic rules included, and it is free and excellent. We would rather tell you that than pretend the trade we made is the only sensible one. What this extension gives you instead is a blocker that structurally cannot watch you, in the same panel as your cookies, your other extensions' permissions and a scan of the site you are on.
When a site breaks
Open the panel on that site and switch off Block on this site. That pauses every list on that one domain and leaves the rest of your browsing filtered; it takes effect on the next page load. Free accounts can hold three paused sites at a time, which is a limit on exceptions rather than on protection — blocking itself is never rationed.
The same lists, in your scans
Blocking is one use for the 99,091 hosts these lists name. The other is on this site: The website scanner matches every third party a page loads against them, so a scan tells you which companies your own visitors are handed to on every page view. That is the advertising and tracking endpoints check, and it is the list a regulator would compile if they asked you about consent.
Where the rules come from
EasyList and EasyPrivacy are maintained by volunteers and used by most of the ad blockers you have heard of. We convert their network rules — “do not load anything from this host” — into the format the browser enforces, with scripts/build_blocklists.py in our repository, so you can regenerate the files yourself and diff the result against what we ship. They are compiled into the package rather than downloaded while you browse, because an extension that fetches a list on a schedule is an extension phoning home on a schedule.
Both lists are published under the GPLv3 and CC BY-SA 3.0 licences. The two converted files carry those terms rather than the MIT licence covering our own code, which rules/LICENSE-FILTERS in the package sets out. Scan.now is not affiliated with or endorsed by the EasyList project.
Frequently asked questions
Is the ad blocker free?
Yes, and it stays that way. Every list is on, every rule is enforced and nothing about blocking is held back for a paid plan. Rationing protection to sell a plan is not something we are willing to do. What a plan changes is how many sites you can scan in a day and how many exceptions the extension will remember for you.
Does it block ads on YouTube?
It blocks the advertising and tracking requests that EasyList and EasyPrivacy name, and some of those are Google's. It does not do anything specific to YouTube, and it does not try to defeat the anti-ad-block detection that sites use. Blockers that do that are in a running battle with the site and break regularly; this is not that.
Will it slow my browsing down?
No, and if anything the opposite. The rules are handed to the browser and enforced inside it, so nothing of ours runs while you browse and there is no code in the request path. A blocked request is a connection your browser never makes, which is time and bandwidth it never spends.
Can it see what I browse?
No. It never sees a request. Blocking is declarative: the browser is given a rule file and enforces it, and the extension is not involved. The counter works by asking the browser how many of our own rules matched, which comes back as a rule number and a timestamp with no URL attached, and the number is stored on your machine.
Why do some ads still get through?
Three reasons, in order of how often they apply. Chrome guarantees an extension 30,000 enforced rules and the full lists hold over 100,000, so we ship the most general ones. Ads served from the same domain as the site cannot be told apart from the site by a network rule. And we do not use cosmetic filters, which hide elements by CSS selector, because applying them means running code inside every page you visit.
How do I stop it breaking a site?
Open the panel on that site and switch off “Block trackers here”. That pauses every list on that one domain and leaves the rest of your browsing filtered. It is one switch and it takes effect on the next page load.
How often are the lists updated?
When we publish a release. The lists are compiled into the package rather than downloaded while you browse, because an extension that fetches a list on a schedule is an extension phoning home on a schedule. The trade is that a brand-new ad domain reaches you at our release pace rather than EasyList's.
It is one of four panels
The same extension scans the site you are on, edits and clears cookies, and audits your other extensions' permissions.