Try Privacy Guardrail: keep personal data out of your AI chats

Customer emails, meeting notes, a colleague’s CV, a stack trace with an API key in it. Most of us have pasted something like that into a chatbot to get a quick summary or a draft reply. The moment you press paste, that text is on its way to an external provider.

Our team at DFKI’s Data Science and its Applications department built Privacy Guardrail to put a check in that moment. It is now public, free and open source, and we need people to use it and tell us where it falls short.

What it does

Privacy Guardrail is a Chrome extension that steps in when you paste text into ChatGPT, Claude or Gemini:

• It scans the pasted text for personal data: email addresses, phone numbers, IBANs, credit card numbers, IP addresses and dates, and, with the optional Local AI model, names, addresses, identifiers and credentials.
• It shows you what it found, and you decide what to replace.
• Replaced parts become placeholders such as [EMAIL_1] or [PERSON_1], so the chatbot never sees the real values.
• When the answer comes back, the extension can put your original values back in, highlighted so you can see what was restored.

Why it runs on your machine

A privacy tool that sends your text to a server to check it would defeat its own purpose. Everything here runs inside your browser: pattern matchers compiled from Rust to WebAssembly, and a compact transformer model for names and other free text. Nothing you paste is sent anywhere to be checked, and the extension has no telemetry or analytics.

What to expect

This is a public beta. It helps you catch personal data before it leaves your machine, but it will not catch everything, and it sometimes flags harmless text. Short names, code blocks and tables are harder. It works in Chrome on desktop with ChatGPT, Claude and Gemini. The Local AI model runs best with plenty of memory and a WebGPU-capable GPU. On smaller machines the extension falls back to pattern-only detection, which still works everywhere.

How you can help

This is where you come in. Three things, in order of effort:

1. Try it. Install Privacy Guardrail from the Chrome Web Store and use it for a week in your normal work.
2. Rate it. Leave a rating and a short review on the Chrome Web Store page. It helps other people find the extension, and it tells us whether it is useful.
3. Tell us what went wrong. Missed something it should have caught? Flagged something harmless? Broke a site? Open an issue on GitHub. Please use made-up or cleaned-up examples only. Never paste real personal data, secrets or private prompts into a public issue. Sensitive security or privacy reports go to pii@dfki.de.

If you write code, the source is on GitHub and contributions are welcome.