LLMReaper is a proof-of-concept Chrome extension (Manifest V3) demonstrating passive DOM-based exfiltration of AI conversations from ChatGPT, Claude, and Gemini using MutationObserver, no special permissions, no network interception. Captured conversations are scanned in real-time for exposed API keys, OAuth tokens, JWTs, cloud credentials, and passwords, then exfiltrated via service worker to bypass Same-Origin Policy. Most users never question the permissions they grant browser extensions.