PromptGnome

Local-first PII detection for AI chatbots. Detects sensitive information in messages you send to ChatGPT, Claude, Gemini, DeepSeek, Perplexity, Grok, Copilot, and Meta AI — before they leave your browser.

PromptGnome is a browser extension (Manifest V3) for Chrome, Firefox, and Edge. Every detection happens on your device. The free tier in this repository makes zero network calls to PromptGnome-controlled servers — you can verify by reading extension/src/ or running gitleaks detect against this repository.

Privacy promise

The free tier:

• Runs entirely on-device. No telemetry, no analytics, no cloud lookups.
• Never transmits the text of your messages anywhere except the AI provider you were already going to send them to.
• Includes regex detection plus optional local NER (using a Hugging-Face-hosted ONNX model loaded into an offscreen document).
• Supports auto-anonymization with re-hydration of placeholders in AI responses.

How it works

Supported providers

• ChatGPT (chatgpt.com, chat.openai.com)
• Claude (claude.ai)
• Gemini (gemini.google.com)
• DeepSeek (chat.deepseek.com)
• Perplexity (perplexity.ai)
• Grok (grok.com, x.com/i/grok)
• Microsoft Copilot (copilot.microsoft.com)
• Meta AI (meta.ai)

Install

Status: v0.1.0 is the first public release. Store listings will be linked here once approved.

• Chrome Web Store: coming soon
• Firefox Add-ons: coming soon
• Edge Add-ons: coming soon

Build it yourself

cd extension
pnpm install --frozen-lockfile
pnpm build

Then in Chrome: chrome://extensions → Developer mode → Load unpacked → select extension/build/chrome-mv3-prod.

For Firefox or Edge:

pnpm build:firefox
pnpm build:edge

Verify the published extension matches this source

Every store-published release is built by GitHub Actions from a tagged commit in this repository. To verify a release:

1. Check out the tag: git checkout v<version>
2. Build: cd extension && pnpm install --frozen-lockfile && pnpm build
3. Compare the SHA256 of extension/build/chrome-mv3-prod/manifest.json against the same file from the GitHub Release artifact.

The release workflow attaches a SHA256SUMS file to every Release.

License

• Repository root: PolyForm Noncommercial 1.0.0 — free for personal, research, educational, and noncommercial use.
• Detection engine (extension/src/detection/): MIT License — broader permission so the regex engine can be reused freely.

For commercial licensing, contact contact@promptgnome.com.

Pro tier

A Pro tier with backend-assisted NER, file and image scanning, and team features is in development. The Pro source code is not in this repository — it lives in a private repository because it depends on backend services that are not part of the open-source promise.

Join the waitlist at https://promptgnome.com/waitlist.

Reporting security issues

Please report security vulnerabilities privately. See SECURITY.md.

Contributing

Pull requests welcome. See CONTRIBUTING.md. All contributors must sign the CLA on their first PR.