We Built a Chrome Extension That Discovered 1,480 Agent-Ready Stores. Here's Exactly How It Works.

Wappalyzer didn't become a 3-million-user tool by being clever. It became essential by answering one question passively: what is this site built with? We built something similar for a different question: is this store agent-ready? The UCP Checker Chrome extension probes /.well-known/ucp on every storefront you visit and shows you the result in your toolbar. Green dot = valid UCP manifest. Gray dot = not detected. Zero clicks required. Six weeks after shipping it, the extension has fed 1,480 unique domains into our monitoring pool — making it our single largest discovery source, ahead of our crawler, web submissions, and bulk checks combined. With a 98.4% verified rate — meaning almost every store it finds has a live, valid manifest. This post is the full technical breakdown: how the detection works, what the permission model looks like compared to other ecommerce extensions, what the extension discovered, and what we're building next. If you read our first post on running 180 agent sho