Rampart

Rampart is a lightweight, on-device privacy protection model developed by the National Design Studio to detect and redact personally identifiable information (PII) before text leaves a user's device. Rather than relying on server-side filtering, Rampart performs token-level PII detection locally, enabling privacy-preserving AI interactions with minimal latency and without exposing sensitive information to external services. The released model is a 14.7 MB ONNX artifact based on a fine-tuned MiniLM-L6-H384 encoder with approximately 18.5 million parameters and a 35-label BIO classification head covering 17 entity types. It works alongside a deterministic recognizer that handles structured identifiers such as phone numbers and IDs, forming a defense-in-depth client-side redaction system. Rampart supports English, Spanish, French, German, Italian, Portuguese, and Dutch, and is designed to run efficiently even on older devices, making it suitable for browsers, mobile and applications.