a2alist.ai

Privacy Policy

x402 Detector Chrome Extension — Last updated: March 6, 2026

Overview

x402 Detector is a browser extension that checks whether websites support the x402 HTTP payment protocol. We are committed to protecting your privacy. This policy explains what data the extension accesses and how it is used.

Data Collection

We do not collect, transmit, or store any personal data.

  • No analytics or tracking scripts
  • No user accounts required
  • No data sent to our servers automatically
  • No browsing history collected
  • No cookies set

Local Storage

The extension stores the following data locally in your browser using chrome.storage.local:

  • Discovered x402 sites — URLs where x402 endpoints were detected, along with payment details (network, price, endpoint path)
  • Notification history — a list of URLs that have already triggered notifications, to avoid duplicates

This data never leaves your browser unless you explicitly use the "Export" or "Submit to a2alist.ai" features.

Network Requests

The extension makes the following network requests:

  • x402 detection probes — HTTP GET/HEAD requests to the current page URL and its /.well-known/x402.json endpoint to check for x402 support
  • Directory listing — fetches the public agent directory from a2alist.ai/api/agents.json when you open the Directory tab in the popup
  • User-initiated submission — when you explicitly click "Submit to a2alist.ai", the extension opens a2alist.ai in a new tab with pre-filled form data

Permissions

Permission Why it's needed
webRequest Monitor HTTP responses for 402 status codes (read-only, main page loads only)
host_permissions Required by webRequest to observe responses on any domain
activeTab Access current tab URL when popup is opened
storage Store discovered sites and notification history locally
notifications Show desktop notification when new x402 site is discovered

Third Parties

No data is shared with third parties. The only external service referenced is a2alist.ai, which is accessed only when you explicitly interact with the Directory tab or Submit feature.

Changes

If this privacy policy changes, the updated version will be posted at this URL. Continued use of the extension constitutes acceptance of any changes.

Contact

For privacy questions, open an issue at github.com/suryast/x402-check.