Show HN: Confidential AI browser extension – alternative to OpenAI Atlas

⚠️ Experimental - not for production use

This Chrome extension is an experimental proof-of-concept designed to validate the feasibility of a confidential AI assistant in the browser.

What to expect:

• Bugs and limited functionality
• No guarantees on maintenance or support
• Browsing history is stored locally without encryption

The Privatemode Chrome extension provides a confidential AI assistant within your browser. It reads the current page and browsing history and can answer questions about it. It keeps all communication with AI confidential, ensuring privacy for sensitive documents, websites, etc.

Under the hood, the extension uses the confidential computing-based AI service Privatemode.

👉 Learn more in this blog post.

1. Create a free Privatemode account.

2. Run the following software locally:

   • 🔒 Privatemode Proxy running on http://localhost:8080. Make sure to enable prompt caching in the proxy to reduce latency and token consumption. The Privatemode Proxy verifies the integrity of the Privatemode AI backend using remote attestation and encrypts your data before sending it to the backend.
   • 📚 Privatemode Document Store running on http://localhost:8081 for document storage and retrieval.

1. Install dependencies:

2. Build the extension:

3. Open the extensions page in Chrome (chrome://extensions) and enable Developer mode by clicking the toggle in the top right corner.

4. Load this folder as unpacked extension.

5. Click the extension icon and use the side panel to send prompts.

🎉 Congratulations. You now have a privacy-preserving chat assistant in your browser.

Want to work on the code of the extension? Great!

When making changes to the code, building and reloading the extension (close + open) is sufficient to apply the changes to a running extension. See below for running the extension as a website for more interactive debugging.

By default, PRIVATEMODE_BASE_URL is http://localhost:8080 and PRIVATEMODE_API_KEY is NONE. If your proxy is started with an API key and does not require a client-provided key, you can leave PRIVATEMODE_API_KEY as NONE.

You can configure the Privatemode endpoint and API key at build time using environment variables. These values are inlined during bundling, so be sure to re-run the build after making any changes.

For quick iteration without loading the Chrome extension, you can serve the side panel as a regular web page.

1. Build the bundle:

2. Start the test server:

3. Open the app in your browser:

   • http://localhost:5173/ (auto-redirects to /sidepanel/)

The page uses the same code as the extension and will call your Privatemode endpoint at http://localhost:8080. To change the server port:

All-in-one (build + serve):

• When updating the extension, the authentication key stored in the document storage service has to be reset to allow the new extension to connect.
• Manifest includes host permissions for http://localhost:8080/* so the extension can reach your local Privatemode instance. When updating the extension, the authentication key stored in the document storage service has to be reset to allow the new extension to connect.

• Local storage security: Browse history is stored in the local file system without encryption or production-grade protection
• Extension implementation: Minimal quality assurance and security review of the extension code
• No support: No committed maintenance schedule or bug fixes
• Breaking changes: May change or break without notice