How to Check Browser Extension Safety

Browser extensions can save time, but they also sit close to the websites you use every day. A useful extension might need to read a page, change its layout or manage a download. The same permissions can expose sensitive information if the extension is poorly maintained or malicious. The right question is not simply “Does this extension have good reviews?” It is “Does this developer need this level of access for the job I want done?”

This checklist covers desktop Google Chrome and Mozilla Firefox. Menu labels can change with browser updates, so use the linked browser documentation if a control looks different on your computer.

1. Start with the official listing, not a download link in a message

Search the Chrome Web Store or Firefox Add-ons directly. Avoid installing a browser extension from a file attached to an email or from an unexpected pop-up. A legitimate-looking website is not proof that a download is safe.

Check the extension’s exact name and publisher. Similar names and icons can make unrelated products look alike. If the developer claims to be a known company, follow the link from that company’s official website to its extension listing rather than relying on a search advertisement.

2. Match the permissions to the promised feature

Before clicking Add, read the permission request. A page translator may need to read text on websites. A password manager may need to detect sign-in forms. Those requests can be understandable, but they still give the extension meaningful access. Mozilla explains that permission to access data on all websites can include reading page contents and information entered into those pages.

Ask three practical questions: What does the extension need to read? What can it change? Does it need access on every site, or only on one or two? A simple color picker that demands access to all your browsing data deserves more scrutiny than one that operates only when you activate it.

Permissions are not a verdict by themselves. Some trustworthy extensions need broad access to work. The point is to understand the trade-off before granting it.

3. Look for signs of a maintained, accountable product

Open the publisher’s website and privacy information from the store listing. Look for a clear description of what data is collected, why it is collected and how support requests are handled. Check whether the extension has been updated recently and whether the developer explains major changes. A long gap between updates is a reason to investigate, not automatic proof of a security problem.

Read a selection of recent reviews, especially reports of unexpected redirects, advertising, account problems or a sudden change in behavior. Treat ratings and download counts as clues rather than guarantees. Reviews can be incomplete, outdated or manipulated, and even a previously useful extension can change ownership or functionality.

4. Limit Chrome site access when the feature allows it

Chrome lets you control website access for many extensions. On a desktop computer, open Chrome’s menu, choose Extensions → Manage extensions, select Details for the extension and inspect its site-access controls. Depending on the extension, options can include access when selected, on specific sites or on all sites.

Choose the narrowest site-access setting that still lets the extension work. For example, a tool used only on one work dashboard generally does not need access to every shopping, banking and email website. Some extensions do not offer the same site-access choices, so check the options shown for that particular extension.

5. Review Firefox permissions and optional access

In desktop Firefox, open the menu and select Extensions and Themes. Choose an extension, then inspect Permissions or Permissions and data. Firefox distinguishes permissions needed by an extension from optional permissions requested for additional features. Where an optional permission has a toggle, you can turn it off and see whether the core feature still works.

Do not assume every permission can be disabled individually. If an extension’s required access is broader than you are comfortable granting, the safer choice may be to remove it and find an alternative with a smaller scope.

6. Test one extension at a time

Install the extension only after checking its listing and permissions. Try its main feature on a non-sensitive page first. Watch for behavior that was not advertised: new search engines, changed homepages, unexpected tabs, injected advertisements or repeated requests to sign in elsewhere.

If something changes unexpectedly, disable the extension and check whether the behavior stops. That is a troubleshooting step, not a complete malware diagnosis. For account-security concerns, visit the affected service directly rather than using links shown by the suspicious extension.

7. Recheck extensions you already installed

An extension audit takes only a few minutes. Open your browser’s extension manager and remove anything you no longer recognize or use. Review access for the tools you keep, particularly extensions that can read data on all websites. Check your browser’s built-in security warnings; Chrome’s Safety Check can flag installed extensions that may pose a risk.

Consider whether the task can be done with a browser feature you already have. Fewer extensions mean fewer publishers and permissions to monitor. If you rely on an extension for passwords, pair this review with our guide to setting up a password manager across devices.

What if you already installed a suspicious extension?

Disable or remove the extension from the browser’s extension manager.
Review any browser settings it may have changed, including your default search engine and startup pages.
If you entered a password into a suspicious page, change that password from the service’s official website and review sign-in activity. Turn on multi-factor authentication where available.
Run an up-to-date security scan if you suspect malicious software on the computer.
For message-based scams, use our phishing warning-sign checklist to help assess the original request.

Removing an extension stops its future browser access; it does not automatically undo information it may already have collected. If sensitive data may have been exposed, address the affected accounts separately.

A quick decision checklist

Source: Is this the authentic publisher’s official extension listing?
Purpose: Can you explain what the extension actually does?
Permissions: Is the requested access proportionate to that purpose?
Accountability: Is there clear privacy information and a way to contact the developer?
Maintenance: Are there recent, credible signs the product is supported?
Control: Can you limit access, or do you need a different tool?

There is no single badge or review score that proves an extension is safe. A careful installation decision combines publisher verification, permissions, data practices and ongoing review.

Sources and image credit

Featured photograph is an illustrative security image by Sasun Bughdaryan, used under the Unsplash License. It does not depict an actual browser permission screen. Source guidance checked October 31, 2026.