How to Check Browser Extension Security: 8 Free Tools and Troubleshooting Tips

Installing a browser extension is simple: one click on "Add to Chrome" and you're done. What's easy to overlook is what happens after the install.

An extension can sit in your browser for months or even years. Depending on the permissions it's granted, it may read page content, access your browsing history, or run scripts inside pages. Not noticing anything unusual doesn't mean those permissions aren't being used.

So when you review extensions, "did antivirus flag it" isn't the right question. A more practical approach is to look at the permissions, the developer, the files, and the browser environment together.

1. Before you scan anything, look at what permissions the extension actually asks for

Chrome users can go straight to: chrome://extensions

Find the extension, open "Details," and start with the permissions it holds and the sites it's allowed to run on.

There's no universal checklist for what counts as reasonable. The key is whether the permissions line up with what the extension actually does.

For example, a translation or web-clipper extension that works on page content reasonably needs access to page content; but if a very simple extension requests a pile of permissions with little to do with its core function, it's worth a closer look.

Firefox users can check extension details under about:addons, and Edge users can use edge://extensions.

This is the first place worth checking, because the permission information comes straight from the browser itself.

2. Don't judge by ratings alone — the developer and update history matter more

Install counts and star ratings are useful reference points, but they shouldn't be the main basis for a security judgment.

When checking an unfamiliar extension, take a minute to see whether the developer has an official website, whether the privacy policy is complete, and what actually changed in the last few updates.

Pay particular attention to one pattern: an extension that has been updated slowly for a long time suddenly shipping frequent releases, along with new permissions or data collection items. That doesn't prove anything is wrong, but it's worth re-checking.

The privacy information on the Chrome Web Store is worth reading too. What matters isn't whether the developer writes "we protect user privacy," but which data they declare collecting and what they use it for.

3. If you suspect the extension files, run them through VirusTotal

If you already have the extension file or the unpacked files, you can run a multi-engine scan with VirusTotal.

It's good at catching files with clearly malicious signatures, but you need to understand its limits: no flags does not mean the extension is safe.

Some extensions have no obvious malicious code — the problem may come from excessive data collection, questionable remote requests, or changes in a later version. File scanning won't necessarily catch any of that.

So VirusTotal works best as a second layer of checks, not as the final verdict.

4. These 8 free browser extension checker entries are worth keeping

Day-to-day extension troubleshooting doesn't require much of a toolkit. The entries below cover permissions, file safety, developer information, and browser environment — mix and match as needed.

Don't treat any single result as the final word on whether an extension is safe. With an unfamiliar extension, combining permissions, file scans, developer information, and environment changes gives you a far more useful read.

5. Check whether the browser environment has changed

Some problems never show up as "malicious file detected" — they show up as changes in the information your browser presents to the outside world. That's when a browser environment check with ToDetect helps.

For example, look at your current IP and network information, DNS, WebRTC, browser fingerprint, Canvas, WebGL, timezone, language, User-Agent, and other parameters, and see whether anything looks clearly off or has shifted over time.

A practical method: when you notice something odd in your browser, record a ToDetect result first, then temporarily disable the extensions you recently installed or updated, and test again to compare.

One important caveat: a change in environment parameters does not prove that a specific extension is behaving maliciously.

ToDetect looks at what the browser and network environment present as a result, not at the extension source code. So it's better for surfacing clues and narrowing down the problem — it can't replace permission checks and code security analysis.

6. When should you just uninstall?

If an extension has gone unused for a long time, the simplest move usually isn't to research whether it's safe — it's to delete it.

For extensions you still need, be cautious if the permissions clearly exceed what the function requires, the developer is hard to verify, the privacy disclosure is vague, or behavior changed noticeably after an update.

More extensions isn't better, either. The fewer you install, the fewer permissions and updates you have to keep track of.

An easy habit: check permissions once before installing, check again after a major update, and clear out unused extensions every few months.

The bottom line

Extension security isn't something you settle once with a single scan. Extensions get updated, developers change hands, and permissions shift as features are added.

So rather than hunting for a one-click "is it safe" tool, it's more effective to know what each entry point can actually tell you: let the browser itself confirm permissions, let a security scanner check the files, and use a tool like ToDetect to watch for environment changes.

A few minutes of cross-checking this information usually clears out a fair number of extensions that don't need to stay in your browser.