x402 Detector

Detects x402 payment protocol endpoints while you browse. Green when found, red when not.

x402 Detector passively checks every site you visit for x402 payment protocol support — the open HTTP payment standard pioneered by Coinbase. HOW IT WORKS • Visit any website — the extension automatically probes for x402 endpoints • Green "x402" badge = site supports x402 crypto payments • Red "OFF" badge = no x402 detected • Click the icon to see payment details (network, price, endpoint) FEATURES • Detects HTTP 402 responses with x-payment-required headers • Discovers endpoints via /.well-known/x402.json • Stores all discovered x402 sites locally • One-click submit to a2alist.ai (the x402 agent directory) • Export discovered sites as JSON • Browse 61+ verified x402 agents from the popup PRIVACY • No data is collected or sent automatically • Submission to a2alist.ai is user-initiated only • All discovered sites stored locally in your browser • No analytics, no tracking, no accounts required BUILT FOR • Developers integrating x402 payments • Crypto enthusiasts exploring the x402 ecosystem • Anyone curious which sites accept crypto via HTTP 402 Part of the x402-validate toolkit: https://github.com/suryast/x402-check Release notes: https://www.npmjs.com/package/x402-validate