Can I grant or revoke permissions after installing an extension?

Yes, partially. For extensions using optional permissions, you can manage individual permissions via the extension's detail page in chrome://extensions. You can also use Chrome's site settings to restrict which sites a specific extension can run on, overriding the extension's host_permissions declaration. Fully revoking core permissions (listed as required in the manifest) typically requires uninstalling the extension.

Do permissions affect performance as well as privacy?

Yes. Extensions with or broad host permissions inject content scripts into every page load, adding a small but measurable overhead to page load times. Extensions with more restricted host permissions only activate on matching pages, reducing background processing. This is another practical reason to prefer extensions with targeted rather than broad permissions.

What happens if an extension requests a new permission in an update?

If an update adds new required permissions, Chrome disables the extension and prompts the user to review and accept the new permissions before re-enabling it. This is an important safeguard that alerts users when an extension's capabilities expand — a sudden new permission request in an update should prompt scrutiny of why that access is now needed.

Browser Extensions

What is Extension Permissions?

Q: What does 'Read and change all your data on websites you visit' actually mean?

This warning corresponds to the host permission (or a broad match pattern like *://*/*). It means the extension's content scripts can run on every website you visit, reading and modifying page content, and the service worker can make network requests to any domain. This is a powerful capability that is legitimate for some tools (ad blockers, password managers) but unnecessary for many others.

Extension permissions are declarations in a Chrome extension's manifest that specify what browser capabilities and web resources the extension is allowed to access. Users see a summary of permissions during installation, and the permissions system is Chrome's primary mechanism for constraining what installed extensions can do.

Last updated: March 6, 2026

Extension Permissions Explained

Every Chrome extension must declare its capabilities upfront in the manifest.json file. These permissions are a contract between the extension and the browser: the extension can only access capabilities it has explicitly declared and been granted. Chrome displays a simplified summary of permissions during installation — the "Add extension" dialog that shows bullets like "Read and change all your data on websites you visit" — and users must accept these terms to proceed. Understanding what different permissions actually enable is essential for evaluating extension safety.

Types of Permissions

Chrome divides extension permissions into several categories. API permissions grant access to specific browser APIs: storage allows reading and writing to Chrome's local key-value store; tabs allows reading tab URLs and titles; cookies allows reading browser cookies for specified sites; downloads allows triggering file downloads. Host permissions specify which websites the extension can interact with and are among the most powerful grants — <all_urls> means the extension's content scripts can run on every site you visit and the service worker can make requests to any origin. Optional permissions can be requested at runtime rather than at install time, allowing extensions to only ask for elevated access when actually needed.

The activeTab Permission

The activeTab permission is a privacy-conscious alternative to broad host permissions. Rather than granting access to all sites always, activeTab gives the extension temporary access to the currently active tab only when the user explicitly invokes the extension (by clicking its icon). This is ideal for extensions that only need to interact with a page when the user asks, rather than running on every page load. Security-conscious extension developers prefer activeTab over <all_urls> wherever possible — users can verify this pattern in the extension's Web Store listing and source code.

Evaluating Permission Scope for Safety

A useful heuristic when reviewing permissions: does the requested access match the stated purpose? A spell checker that requests access to all websites is reasonable — it needs to read text fields everywhere. A weather extension that requests <all_urls> is suspicious — why would it need to run on every website? Equally concerning are extensions requesting cookies, webRequest, or browsingData permissions without a clear functional reason, as these enable surveillance-level data collection. The Manifest V3 transition improved this somewhat by separating host_permissions into their own field, making the scope of site access clearer at a glance.

How PlugMonkey Extensions Use Permissions

Extensions like X Unfollow Pro and Instagram Followers Exporter Pro request host permissions only for the specific platforms they operate on (x.com and instagram.com respectively), plus storage access for saving your data locally. They do not request access to all websites, cookies, or browsing history — permissions they have no functional need for. This principle of least privilege — requesting only what is needed — is a meaningful trust signal when evaluating any extension.

Real-World Examples

An extension requesting 'Read and change all your data on all websites' has the <all_urls> host permission — the broadest possible site access grant.

X Unfollow Pro declares host_permissions for 'https://x.com/*' only, meaning its content scripts cannot run on any other website.

A password manager extension requests the 'cookies' permission to implement auto-login, which is functionally justified but represents a powerful capability that a malicious extension could abuse.

An extension using activeTab shows 'Read your data on the current active tab' in the install dialog — a more limited and user-controlled permission than all-sites access.