What Your Browser Extensions Can Actually See

A coupon finder. A grammar checker. A screenshot tool. Small browser extensions solve small, specific problems, and most people install a handful without much thought — a quick click on a browser’s extension store, and it is running in the background from that point forward.

What many of those extensions can technically see is far broader than the one job they claim to do. And unlike an app on your phone, a browser extension often has a front-row seat to everything you look at online.

To do their job, many extensions request a permission along the lines of “read and change all your data on the websites you visit.” That phrase is not an exaggeration — it means exactly what it says. A grammar checker needs to read the text on a page to check it, which technically means it is capable of reading everything else on that page too, including things that have nothing to do with grammar.

Most extensions that ask for this level of access are not doing anything questionable with it. But the permission itself does not distinguish between an extension using that access responsibly and one that is not. Once granted, the extension has the technical capability either way.

With broad page access, an extension is technically positioned to see form fields as you type into them, including login screens and payment pages. It can see the content of private messages and emails displayed on screen. It can track which sites you visit and how long you stay, building a browsing profile that can be sold to advertisers or data brokers.

This is not a hypothetical concern. There have been repeated, documented cases of popular browser extensions — some with millions of installs — quietly collecting and selling detailed browsing data, or being sold to a new owner who changed the extension’s behavior without most users ever noticing the switch.

Most browsers keep an extensions management page where you can review everything currently installed, along with the permissions each one was granted.

Open your extensions list. In Chrome, Edge, or most Chromium-based browsers, this is usually found through the puzzle-piece icon in the toolbar, or by typing the browser’s extensions address directly into the address bar. Firefox keeps a similar list under its Add-ons manager.

Review what is actually installed. It is common to find extensions that were installed once for a single task, months or years ago, and simply forgotten. Each one still has whatever permissions it was originally granted, still running in the background.

Check the permissions, not just the name. Most browsers let you view exactly what access each extension has. Look specifically for anything requesting access to “all sites” or “read and change all your data” and ask whether that level of access actually matches what the extension is supposed to do.

Remove what you do not actively use. If you cannot remember installing something, or have not used it in months, removing it costs nothing and closes a door that did not need to stay open.

Before installing a new extension, a quick check of the requested permissions against the tool’s actual purpose is worth the thirty seconds it takes. A simple ad blocker asking for access to everything you type is worth a second look before clicking install.

Extensions are genuinely useful, and most are exactly what they claim to be. The habit worth building is not avoiding them entirely — it is knowing what you have granted access to, and clearing out what you no longer need.