How to Check If a Browser Extension Is Safe (2026)
Browser extensions have direct access to your browsing data, passwords, and online activity. In 2025, malicious extensions stole data from over 2.3 million users. Here is exactly how to audit any extension before you install it.
The Problem Is Bigger Than You Think
In late 2025, security researchers discovered a campaign of over 30 malicious Chrome extensions that had been stealing data for months. Some had Featured badges in the Chrome Web Store. Some had millions of downloads. Users had no idea their browsing history, cookies, and login sessions were being exfiltrated to remote servers.
This is not an edge case. Browser extensions operate with privileged access inside your browser. A single extension with the wrong permissions can see every website you visit, read your passwords as you type them, capture your clipboard contents, and modify the pages you see. The Chrome Web Store's review process catches many threats, but it is not perfect.
The good news: you can evaluate an extension's risk yourself by understanding what its permissions actually mean.
How to Find an Extension's Permissions
Before analyzing permissions, you need to find them.
The 4 Permission Risk Levels
Not all permissions are equal. We categorize them into four risk levels based on what they can access and the potential for abuse.
Audit any extension in seconds
Select the permissions your extension requests and get a security risk score with detailed explanations and recommendations. 100% client-side.
Audit an Extension →Dangerous Permission Combinations
Some permissions are more dangerous in combination than alone. These are the pairings that should raise immediate red flags:
We Audited 6 Common Extension Types
To show what typical permission profiles look like, we ran six common extension categories through TrustScan's Extension Security Auditor.
| Type | Score | Risk | Key Concern |
|---|---|---|---|
| Dark Mode | 82/100 | 🟢 Low | Minimal permissions — just active tab and storage |
| Ad Blocker | 49/100 | 🟡 Medium | Needs web request interception to function, but this is powerful |
| Screenshot Tool | 40/100 | 🟡 Medium | Page capture + downloads + tab access |
| Grammarly-type | 24/100 | 🔴 High | All websites + cookies — can see everything you type |
| VPN Extension | 20/100 | 🔴 High | Proxy + web request — routes and monitors all traffic |
| Password Manager | 19/100 | 🔴 High | All websites + clipboard — necessary but extremely powerful |
Notice that password managers and VPN extensions score as High Risk. This does not mean they are malicious — it means their permissions are inherently powerful. These tools need broad access to function. The key is making sure you trust the developer, the extension has a strong track record, and the source code is auditable.
5 Rules for Browser Extension Safety
Audit Your Extensions Now
Every extension in your browser has a permission profile that determines exactly what it can access. Most people never check. TrustScan's Extension Security Auditor lets you select an extension's permissions and instantly see a risk score, detailed explanations, dangerous combinations, and specific recommendations. It runs 100% in your browser with no data sent anywhere.
Start by auditing the extension you use most. The results might surprise you.
Cybersecurity professionals building free privacy tools for the 2026 compliance landscape.