Security

Are Browser Extensions Safe?

An extension is a small program with access to your browser. Many ask for permission to read and change every site you visit. That is how a coupon tool or a color picker can end up seeing your banking pages.

Last updated October 14, 2026 · By Harbor Privacy

Why Extensions Are a Risk

Extensions run with the permissions you grant. An extension allowed to read and change data on all websites can see what you type and what each page shows. Extensions are also bought and sold. A tool that was harmless can be sold to a new owner who changes what it does in an update.

Researchers regularly find popular extensions quietly collecting browsing history and selling it.

Audit What You Have

Open your extensions listChrome and Edge: the puzzle-piece menu, then Manage extensions. Firefox: Add-ons and themes.

Remove what you do not useIf you cannot say why you have it, remove it.

Check each permissionOpen Details and see which sites it can access.

Limit site accessSet extensions to run only when you click them, or only on specific sites.

Warning Signs

Access to all sites for a tool that only needs one
Few reviews, or a sudden change of developer or ownership
A free tool with no clear way it makes money
Search or new-tab pages changed after installing

Fewer Extensions, Same Protection

Blocking ads and trackers at the DNS level removes the need for some extensions, because nothing is added to your browser. See How to Block Ads on Every Device at Home and Private Browser Setup.

Common Questions

Are extensions from the official store safe?

They are reviewed, but malicious and data-collecting extensions have passed review. The store is a filter, not a guarantee.

How many extensions is too many?

There is no number. Each one is another program with access to your pages, so keep only the ones you actually use.

Are ad blockers safe?

Well-known open-source blockers are widely audited. Be careful with unknown ones, since a blocker has access to every page by design.

Do extensions work in private windows?

Usually not, unless you allow them. It is a useful setting to leave off.

LESS IN YOUR BROWSER

Harbor Adblock blocks ads and trackers for every browser and app with nothing installed. From $1.99 a month with a 30-day free trial. See Harbor Adblock.