Rampart: open-source, on-device PII redaction in the browser

Rampart is an open-source, first-generation PII filter that runs entirely in the browser, redacting personal information from chat messages before they are sent to a remote server. It combines a deterministic regular-expression layer for structured identifiers such as Social Security numbers and credit cards with MiniLM, a small language model, which catches names and street addresses. The article reports a 14.7 MB model size, 3.9 ms p50 latency on WebGPU, and 98.42% private-term recall on a 30,000-row held-out OpenPII slice, compared with 94.2% for GLiNER small v2.1 at about 600 MB. It is described as an alpha product that currently supports seven Latin-script languages: English, Spanish, French, German, Italian, Portuguese, and Dutch.