Web Request Blocking

webRequestBlocking

High RiskCategory: Web Traffic ControlView Official Docs↗

Technical Context

Extends webRequest with the ability to synchronously intercept, modify, redirect, or cancel network requests. This powerful capability is used by ad blockers, privacy tools, and security extensions to filter web traffic.

What This Means For You

The extension can block, redirect, or modify any request your browser makes before it happens. This is how ad blockers work, but it also means the extension controls what data reaches websites.

Related APIs

This permission enables access to these Chrome APIs:

chrome.webRequest

Common Use Cases

✓Ad blockers
✓Privacy shields
✓Parental controls

⚠ Red Flags When Combined With

cookies <all_urls>

How to Declare in manifest.json

Add the "webRequestBlocking" permission to your extension manifest:

{
  "manifest_version": 3,
  "name": "My Extension",
  "permissions": [
    "webRequestBlocking"
  ]
}

Related Permissions

Web Request Auth Provider

webRequestAuthProvider

The extension can automatically provide usernames and passwords when websites request them through browser popup dialogs. This is useful for corporate proxies or secured intranet sites.

high

Proxy

proxy

The extension can redirect all your internet traffic through a different server before it reaches websites. This is powerful for privacy but means the proxy server sees all your browsing.

high

VPN Provider

vpnProvider

The extension can route all your internet traffic through a VPN tunnel. This encrypts your browsing but means the VPN provider sees all your traffic.

high

Cookies

cookies

The extension can see the small "id cards" websites use to remember that you are logged in. This allows the tool to help you manage your privacy or stay signed into multiple accounts simultaneously.

high

Web Request

webRequest

The extension can see the network requests your browser makes, like which images or scripts a page loads. By itself, it can only watch traffic, not change it.

medium