Browser extensions as trackers
Why it matters Browser extensions can be wonderful, but some see every page you visit. A handful of minutes checking what yours are allowed to do can close one of the widest windows into your browsing.
A key to every room
A third-party script is a contractor with a key to one house. An extension with broad permissions is a contractor with a key to every house you ever visit: your bank, your email and your shopping. Most use that key honestly. The point is to know who holds it.
Browser extension (add-on): a small program you install into your browser to add features, such as a password manager, ad blocker or coupon finder.
Permission: what the browser allows an extension to do. You see these when you install it.
Reading the permission warnings
| The warning says | In plain words |
|---|---|
| Read and change all your data on all websites | It can see and alter every page you open, including what you type into forms. |
| Read your browsing history | It can list every site you have been to. |
| Read and change your data on shopa.example | It works only on that one site. Much narrower. |
| Manage your downloads | It can see and start downloads. |
Some tools genuinely need wide access: an ad blocker must see every page to block ads on it. The question to ask is "does this job need this much?" A tool that changes the colour of one site does not need your whole history.
How good extensions turn bad
- Sold extensions. A popular extension can be bought by a new owner, who ships an update that starts collecting browsing data. Extensions update automatically, so you may not notice.
- "Free" with a catch. Some free tools pay their way by collecting and selling what they see.
- Tighter rules help, but not fully. Browsers have tightened what extensions may do (checked October 2026), for example limiting code downloaded after install. But an extension allowed to read pages can still read them.
Try it List your extensions and their access. In Chrome or Edge, type chrome://extensions (or edge://extensions) in the address bar and press Enter, then click Details on each one. Under Site access you can choose "On click" or "On specific sites" instead of "On all sites" (checked October 2026). In Firefox, type about:addons, choose an add-on and open its Permissions tab.
- Remove anything you no longer use.
- For the rest, narrow site access where the option exists.
These are your own settings; nothing is sent.
A common misconception
"It is in the official store, so it is safe." Store reviews catch a lot, but not everything, and an extension that was safe last year may have changed owner. Fewer extensions, with narrower access, is the safest habit.
Recap
- An extension with "all websites" access can read and change every page, including what you type.
- Ask whether its job needs that much access.
- Extensions can change owners and behaviour through automatic updates.
- Remove unused extensions and narrow site access to "On click" where you can.
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