pay.json

An open standard for machine-readable pricing — like robots.txt but for payments.

pay.json tells AI agents what content costs and how to pay for it. Publishers place a pay.json file at their domain root (/.well-known/pay.json) describing pricing rules and accepted payment methods.

Quick Example

{
  "version": "1.2",
  "protocol": "x402",
  "network": "base",
  "asset": "USDC",
  "receiver": "0x1234567890abcdef1234567890abcdef12345678",
  "seller_wallet": "0x1234567890abcdef1234567890abcdef12345678",
  "facilitators": [
    { "name": "payai", "url": "https://facilitator.payai.network", "priority": 1, "spec_version": "v2" },
    { "name": "xpay",  "url": "https://facilitator.xpay.sh",       "priority": 2, "spec_version": "v2" }
  ],
  "rules": [
    { "path": "/blog/*",    "price_usd": "0.003" },
    { "path": "/premium/*", "price_usd": "0.01"  }
  ]
}

facilitators[] lets the publisher list which x402 facilitators they accept. Agents try them in order and fall back through the list. No single intermediary sits in the money path.

Specification

The full spec lives in spec/.

Tools

Validation and generation tools in tools/.

License

• Specification: CC-BY-4.0
• Code/tools: MIT