Choosing a tracker blocker extension, and why you only want one
The browser is the gap that whole-house filtering and device settings cannot reach. Installing several blockers makes things worse, not better.
Two earlier articles said the same thing. Tidying your iPhone’s settings does not reach a third-party browser, and whole-house DNS filtering gets walked past by browsers that encrypt their own DNS queries.
The browser goes its own way. An extension is what fills that gap.
An extension does a different job from DNS filtering
Both say they “block tracking”, but they are looking at different things.
| DNS filtering | Browser extension | |
|---|---|---|
| What it judges on | The address (domain) | What runs inside the page, and how |
| Reach | Every device in the house | That one browser |
| Tracking from the same domain | Can’t separate it | Can pick it out |
| Hiding page elements | No | Yes |
So they are not substitutes. They are complements. DNS covers breadth; the extension covers depth.
Install exactly one
This is the part people most often get wrong. Several blockers feels like more blocking, and it usually ends up worse.
- Two of them handling the same request collide and break the page
- You cannot tell which one blocked what, which makes exceptions impossible
- The browser slows down, because every request passes through two inspection stages
Staying in a state where you can identify the cause matters more than widening coverage slightly. Pick one and tighten its settings if it isn’t enough.
What to judge them on
Criteria outlast names, so start here.
① Is it open source, with public lists? You should be able to see what it blocks. A blocker sits where it can see every request, which makes the blocker itself something you are trusting.
② What is the business model? If it is free and the company is still running, money is coming from somewhere. Charging advertisers to be allowlisted is a model that genuinely exists. Check whether such a list is on by default.
③ Is it still being updated? Tracking techniques keep changing. A last update two years ago means it is already behind.
④ How much permission does it ask for? Blockers legitimately need broad access, but some ask for more than that.
What is actually out there
Criteria alone are hard to act on, so here are the common ones measured against them. Names change; the structure behind each one rarely does.
| What it is | Business model | |
|---|---|---|
| uBlock Origin | Open source, list-based, treated as the reference point | None. Donations only |
| uBlock Origin Lite | The MV3 version of the above. Its own docs say it works “entirely declaratively” | None |
| AdGuard | An extension plus separate apps | Free tier, then paid |
| Privacy Badger (EFF) | Learns by observation rather than lists. Made by the Electronic Frontier Foundation | Non-profit |
| Adblock Plus / AdBlock | Runs an “acceptable ads” programme openly | Advertisers pay to be on the allowlist |
That last row is criterion ② in the flesh. It is a published business model rather than something hidden, and the list is on by default. You can switch it off, so go and look.
Privacy Badger works differently. Instead of taking a list, it watches whether the same party keeps showing up across sites and decides from that. It blocks less at first and more as you use it. Fewer broken pages, less immediate effect.
If you use Chrome, things have changed
This is the most time-sensitive part of this article.
As Google moved extensions to its new format, all remaining old-format extensions were removed from the Chrome Web Store on 31 August 2026. uBlock Origin is among them. If you were running it on Chrome you have probably already seen the “this extension may soon no longer be supported” notice.
There are three ways out.
- Move to uBlock Origin Lite. Same team, built for the new format, and the default block lists are still there. It works “entirely declaratively”, which means it does not make the same in-the-moment judgements the old one did
- Use a different blocker built for the new format
- Change browser. Firefox is not affected by this change
Edge and Opera still work today, but Edge began the same transition in August 2026 and aims to finish it by the end of the year (business accounts follow in early 2027). If you are using it there, treat it as borrowed time.
This section is pinned to a date. If you are reading it much later, check the extension’s own repository for where things stand.
Turn on what the browser already has first
Before installing anything, switch on what is already built in. Nothing to collide with, and nothing to get removed.
- Safari — Settings, Privacy: Prevent Cross-Site Tracking, Hide IP Address
- Firefox — Enhanced Tracking Protection on Strict
- Chrome — weaker tracking protection than the others. It needs an extension most, and for the reason above it has fewer to choose from
- Edge — Tracking prevention on Strict
For plenty of people the built-in settings are enough. An extension goes on top of that.
Learn how to undo it before you need to
Use a blocker long enough and a page will break. A payment won’t go through, a login box won’t appear, a video won’t play.
Don’t uninstall it on the spot. Nearly every blocker has pause on this site. Try that first; if it fixes things you have found the cause and can make that one site an exception.
Delete it and you never learn what the problem was, and you repeat the whole thing when you install it again.
What still gets through
Even with an extension, the same limits as in the VPN article remain.
- Accounts you log into. Sign in and that service knows who you are
- Browser fingerprinting. Identifying you by screen size and font list sits at a different layer from blocking requests
- Anything inside an app. An extension does not leave the browser. That is DNS filtering’s job
In short
| Question | Answer |
|---|---|
| Why do I need one if I have DNS filtering | Browsers walk past that setting |
| How many should I install | One. Several collide and hide the cause |
| What first | The browser’s own tracking protection, on Strict |
| How to judge one | Public lists, business model, updates, permissions |
| When a page breaks | Don’t delete it. Pause it on that site |
| Does this make me anonymous | No. Logins and fingerprinting are untouched |
| If I use Chrome | Old-format extensions went on 31 Aug 2026. Move to a new-format one |
The summary is DNS for breadth, one extension for depth. Knowing which tool covers what lasts longer than adding more of them.