PasteGuard (LLM Sanitizer)

A privacy-first browser extension that intercepts paste events and automatically redacts sensitive information — emails, phone numbers, API keys, and more — before it reaches AI chatbots. Your secrets stay yours.

Browser Extension

JavaScript

Security

The Overview

PasteGuard is a browser extension built with a single mission: prevent accidental data leaks into AI chatbots. Every time you paste text into a supported LLM interface, PasteGuard silently scans the clipboard content for personally identifiable information (PII) and sensitive data patterns — including emails, phone numbers, credit card numbers, API keys, and custom regex rules you define. Detected items are instantly replaced with safe placeholders like [EMAIL_REDACTED] before the text ever reaches the input field. All processing happens 100% locally in your browser with zero external network calls, ensuring your data never leaves your device.

Key Features

Real-time clipboard scanning on every paste event

Regex-based PII detection for emails, phone numbers, API keys, and more

Customizable redaction rules and sensitivity levels

100% local processing — zero data sent externally

Visual diff preview showing what was redacted before confirming

The Journey

"Ensuring zero perceptible latency during paste events while accurately parsing complex and overlapping string patterns — such as distinguishing a valid API key from a harmless alphanumeric string — without triggering false positives was the central engineering challenge. Balancing aggressive detection with a frictionless user experience required extensive regex tuning and edge-case testing across diverse clipboard contents."

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