PostHog Blocker: A Chrome extension to block yourself from PostHog

Overview

PostHog Self-Blocker is a Manifest V3 Chrome extension that gives you full control over PostHog analytics and session recordings. By maintaining a domain allowlist, the extension intercepts PostHog’s API calls and network requests, ensuring no data is sent to PostHog on sites you choose to block.

Features

• Block PostHog analytics and session recordings on exact domains and all subdomains
• Dynamic network blocking via Chrome’s declarativeNetRequest API
• JavaScript API interception with a no-operation stub injected at document start
• Domain list stored and synced across browsers using chrome.storage.sync
• Clean, responsive options UI with dark mode support
• Real-time updates—no page reload required

Technical Details

This project is built with plain JavaScript using Chrome Extension Manifest V3:

• manifest.json
• Declares permissions: storage, declarativeNetRequest, <all_urls>
• Registers the background service worker and content script

• background.js
• Reads the blocked-domains list from chrome.storage.sync
• Clears old dynamic rules and installs new blocking rules for PostHog endpoints (eu.i.posthog.com)
• Listens to storage, install, and startup events to keep rules in sync

• content_script.js
• Runs at document_start on all pages
• Checks if the current hostname matches any blocked domain or subdomain
• Defines a stubbed window.posthog object to no-op all API calls

• options.html & options.js
• Provide a UI for adding, removing, and searching domains in the blocked list
• Sync user changes in real time and trigger a background rule refresh

• rules.json
• (Optional) Static rules template for network request interception

How It Works

1. Domain Management
   Users add domains in the options page; the list is saved to chrome.storage.sync.
2. Rule Sync
   On install, startup, or storage change, background.js rebuilds all blocking rules via declarativeNetRequest.updateDynamicRules.
3. Network Blocking
   Requests to PostHog’s API (eu.i.posthog.com) are blocked before they leave the browser.
4. API Interception
   A content script injects before the page loads, overriding window.posthog with a stub that quietly ignores all calls.

Project Structure

• manifest.json
• background.js
• content_script.js
• options.html
• options.js
• rules.json
• README.md
• screenshot.png
• icon128.png
• icon128_white.png

Installation & Usage

1. Install from the Chrome Web Store here
2. Or load unpacked:
   • Clone the repository
   • Go to chrome://extensions/ and enable Developer mode
   • Click “Load unpacked” and select the extension folder
3. Click the extension icon, add domains to block, and enjoy privacy without rebuilding or reloading pages.