Drawbridge

On-device PII pseudonymization for AI chat, powered by the Rampart model. Real values never leave your machine.

Drawbridge protects your personal information before it reaches AI chat sites. Powered by the on-device Rampart model, it detects names, addresses, phone numbers, emails, SSNs, credit cards, and more — then replaces them with stable placeholder tokens like [GIVEN_NAME_1] before your message is sent. The AI site only ever sees the placeholder, while Drawbridge restores the real values in replies right on your device. How it works: - As you type, detected PII is highlighted in the composer and a chip shows how many items will be protected. - When you hit send, the real prompt is swapped for a protected version on the wire. - When the AI replies, placeholder tokens are restored to real values locally before they reach your eyes. Key features: - On-device processing: the 14.7 MB Rampart model runs locally in your browser via WebGPU/WASM. No data sent to any external service for detection. - Fail-closed by default: if the model can't scan a message in time, sending is blocked rather than letting raw text through. - Supports claude.ai (first surface; architecture is site-agnostic). Honest limitations: - Rampart is ~98.4% recall — a strong first line of defense, not a guarantee. - Text messages only; attachments, file uploads, and pasted images are not scanned. - Interception covers fetch only (claude.ai uses fetch today). - Session tables are in-memory only; after a browser restart, historical placeholders may not restore correctly until a new conversation starts. Permissions: - Storage: to save your settings locally. - Scripting: to inject content scripts on supported sites. - Offscreen: to host the Rampart model in a dedicated execution context.