Chrome extensions are small programs that add features to your browser
A Chrome extension is a piece of software that installs into Google Chrome and changes what your browser can do. Extensions live in your browser toolbar, run in the background, or both. They can block ads, save passwords, translate web pages, take screenshots, check grammar, or dozens of other things — but they only work inside Chrome itself, not on your computer as a whole.
When you install an extension, it asks for permission to do certain things: read what's on the pages you visit, see your browsing history, access your clipboard, or store data locally. You decide whether to grant those permissions. If you later change your mind, you can turn the extension off, remove it entirely, or change what it's allowed to do.
Extensions are different from browser settings. A setting is built into Chrome. An extension is something you add on top. This matters because an extension can see more of what you do online than Chrome's built-in features can, and it comes from a third party — not Google — so you're trusting someone else's code to run on your machine.
Key Takeaways
- Extensions add new features to Chrome by running code inside your browser, and they ask for permission to access specific information like the pages you visit or your passwords.
- Each extension can see and do different things depending on the permissions you grant, so checking what an extension asks for before you install it matters for your privacy.
- Extensions come from the Chrome Web Store, from developers' own websites, or from third-party sites, and only the Web Store extensions are reviewed by Google before they go live.
- You can turn extensions on and off without removing them, change their permissions at any time, or delete them completely if you no longer want them.
- Some extensions are safer than others because they ask for fewer permissions, come from well-known makers, or have been around long enough that problems would have surfaced.
How extensions ask for permission and what they can access
When you install an extension, Chrome shows you a list of permissions it wants. These are not optional — the extension needs them to work. Common permissions include "read and change all your data on websites you visit," "see your browsing history," "manage your downloads," or "read your clipboard." Some extensions ask for broad access; others ask for very little.
The permission "read and change all your data on websites you visit" is the broadest one. It means the extension can see everything you type into a form, every password field you fill, every search you enter, and every page you land on. An extension with this permission could theoretically steal your login information or watch what you do on banking sites. This is why the source of the extension matters — you're trusting the maker not to abuse that access.
Other permissions are narrower. "See your browsing history" means the extension can look at the list of sites you've visited, but not necessarily see what you did on those sites. "Manage your downloads" means it can see what files you've saved. "Access your tabs" means it knows which pages you have open right now. You can see the full list of permissions for any installed extension by going to chrome://extensions, clicking the extension, and looking at the "Permissions" section.
Where extensions come from and which sources are safer
The Chrome Web Store is Google's official marketplace for extensions. Before an extension appears there, Google reviews it for malware and checks that it does what it claims to do. This does not mean every extension in the Web Store is safe — Google's review is automated and human reviewers cannot catch everything — but it is a basic filter. Extensions in the Web Store are also easier to update, and you can see user reviews and ratings.
Some developers host extensions on their own websites or GitHub. These extensions are not reviewed by Google before you install them. You have to trust the developer's reputation and read the code yourself if you know how. This route is less common for everyday users but more common for technical extensions or ones made by small teams.
Third-party sites sometimes offer extensions too, and this is where risk goes up. A site might host an old version of a popular extension, a fake version with a similar name, or something that looks legitimate but contains malware. Stick to the Chrome Web Store unless you have a specific reason to trust the source and you understand what you're installing.
The difference between what an extension sees and what it stores
An extension can see something without keeping it. For example, a grammar-checking extension might read every sentence you type into a web form, check it for errors, and then forget it. It saw your words but did not store them. A password manager, by contrast, sees your passwords and stores them — that's the whole point.
Some extensions send data back to the maker's servers. A translation extension might send the text you want translated to the company's servers so it can process it. A weather extension sends your location. A search tool sends your search terms. Others work entirely offline and never send anything anywhere. You can sometimes see what an extension sends by looking at its privacy policy, though many privacy policies are vague.
If you want to know what an extension is actually doing, you can look at its network activity using Chrome's developer tools (Ctrl+Shift+I on Windows, Cmd+Option+I on Mac, then the Network tab). This shows you what data the extension is sending and where it's going. Most people don't do this, but it's an option if you're suspicious about a particular extension.
How to install, turn off, and remove extensions
To install an extension from the Chrome Web Store, go to chrome.google.com/webstore, search for what you want, click the extension, and click "Add to Chrome." Chrome will ask you to confirm the permissions. Click "Add extension" and it's installed.
Once installed, the extension usually appears as an icon in your toolbar (the row of icons to the right of the address bar). Click the icon to open the extension's menu or settings. Some extensions run silently in the background and don't have a visible icon.
To turn an extension off without removing it, go to chrome://extensions, find the extension in the list, and toggle the switch to "Off." The extension is still installed but not running. To turn it back on, toggle the switch again. To remove it entirely, click the trash icon next to the extension's name.
You can also change what an extension is allowed to do. On the chrome://extensions page, click the extension, scroll to "Permissions," and click "Site access." You can choose to let the extension run on all sites, only on sites you choose, or not at all. This is useful if you trust an extension but don't want it reading your data on sensitive sites like your bank.
Why some extensions slow down your browser and how to check
Each extension uses memory and processing power. If you install many extensions, or if an extension is poorly written, your browser will slow down. Pages take longer to load, scrolling feels sluggish, and opening new tabs takes extra time. This is especially noticeable on older computers or if you have many tabs open.
To see which extensions are using the most resources, go to chrome://system and look for "Extensions" in the list, or use Chrome's built-in task manager by pressing Shift+Esc. The task manager shows you how much memory and CPU each extension is using. If one extension is using a lot, you can turn it off or remove it.
The simplest way to speed up Chrome is to remove extensions you don't use regularly. If you installed something months ago and never use it, delete it. If you have five ad blockers, keep the one you like best and remove the others. Fewer extensions means faster browsing.
Red flags that suggest an extension might not be trustworthy
An extension asking for more permissions than it needs is a red flag. A straightforward note-taking extension should not need to see your browsing history or access your passwords. A weather extension should not need to read all your data on all websites. If the permissions don't match what the extension claims to do, skip it.
An extension with very few reviews, very recent reviews that all say the same thing, or reviews that mention it stealing data or slowing down the browser is a sign to look elsewhere. Read a few reviews before installing anything, especially if it's from a developer you've never heard of.
An extension that has not been updated in years might contain security holes that have since been discovered. Go to the extension's page in the Chrome Web Store and look at the "Last updated" date. If it says "2 years ago" or longer, the developer may have abandoned it. This does not always mean it's unsafe, but it's a reason to be cautious.
Extensions with names very similar to popular ones — like "Adblock Pro" instead of "Adblock Plus" — are sometimes fakes designed to trick you. Check the developer's name and the number of users. A fake usually has far fewer users than the real thing.
Frequently Asked Questions
Can an extension see my passwords even if I don't give it permission?
No. Chrome's password manager is separate from extensions. An extension can only see passwords if you give it explicit permission to "read and change all your data on websites you visit," which is a very broad permission. Even then, Chrome's password fields are somewhat protected. Never install an extension that claims it needs to see your passwords unless it's a legitimate password manager like Bitwarden or 1Password.
What happens if I remove an extension and then reinstall it?
If you remove an extension, any data it stored locally (like settings or saved notes) is deleted. If you reinstall it, you start fresh. Some extensions sync their data to the developer's servers, so reinstalling might restore your settings if you log back in. Check the extension's settings before removing it if you want to keep your data.
Do extensions work on Chrome on my phone?
Chrome on Android and iPhone does not support extensions the way desktop Chrome does. You can install some extensions on Chrome on Android, but the selection is very limited and most desktop extensions are not available. iPhone's Chrome does not support extensions at all.
Is it safe to use multiple ad-blocking extensions at the same time?
It's not dangerous, but it's unnecessary and will slow your browser down. Multiple ad blockers do roughly the same job, so you're wasting resources. Pick one you like and remove the others. If one is not blocking all the ads you want blocked, switch to a different one rather than stacking them.
Can I see what data an extension is sending to its maker?
You can use Chrome's developer tools (Network tab) to see what servers an extension is contacting and what data it's sending. Most people don't do this, but it's possible if you're technically inclined. The extension's privacy policy should also explain what data it collects, though policies are often vague or buried in legal language.