Publish your UCP profile at /.well-known/ucp, as shown in the following
example:
{
"ucp": {
"version": "2026-01-23",
"services": {
"dev.ucp.shopping": [
{
"version": "2026-01-23",
"spec": "https://ucp.dev/specification/overview",
"transport": "rest",
"endpoint": "https://business.example.com/ucp/v1",
"schema": "https://ucp.dev/2026-01-23/services/shopping/openapi.json"
}
]
},
"capabilities": {
"dev.ucp.shopping.checkout": [
{
"version": "2026-01-23",
"spec": "https://ucp.dev/specification/checkout",
"schema": "https://ucp.dev/2026-01-23/schemas/shopping/checkout.json"
}
],
"dev.ucp.shopping.fulfillment": [
{
"version": "2026-01-23",
"spec": "https://ucp.dev/specification/fulfillment",
"schema": "https://ucp.dev/2026-01-23/schemas/shopping/fulfillment.json",
"extends": "dev.ucp.shopping.checkout"
}
],
"dev.ucp.shopping.discount": [
{
"version": "2026-01-23",
"spec": "https://ucp.dev/specification/discount",
"schema": "https://ucp.dev/2026-01-23/schemas/shopping/discount.json",
"extends": "dev.ucp.shopping.checkout"
}
],
"dev.ucp.shopping.order": [
{
"version": "2026-01-23",
"spec": "https://ucp.dev/latest/specification/order",
"schema": "https://ucp.dev/2026-01-23/schemas/shopping/order.json"
}
]
},
"payment_handlers": {
"com.google.pay": [
{
"id": "8c9202bd-63cc-4241-8d24-d57ce69ea31c",
"version": "2026-01-23",
"spec": "https://pay.google.com/gp/p/ucp/2026-01-23/",
"schema": "https://pay.google.com/gp/p/ucp/2026-01-23/schemas/config.json",
"config": {
"api_version": 2,
"api_version_minor": 0,
"environment": "TEST",
"merchant_info": {
"merchant_name": "Example Merchant",
"merchant_id": "01234567890123456789",
"merchant_origin": "checkout.merchant.com"
},
"allowed_payment_methods": [
{
"type": "CARD",
"parameters": {
"allowed_auth_methods": [ "PAN_ONLY" ],
"allowed_card_networks": [
"AMEX",
"DISCOVER",
"JCB",
"MASTERCARD",
"VISA"
],
"billing_address_required": true,
"billing_address_parameters": {
"format": "FULL",
"phone_number_required": true
}
},
"tokenization_specification": {
"type": "PAYMENT_GATEWAY",
"parameters": {
"gateway": "example",
"gatewayMerchantId": "exampleGatewayMerchantId"
}
}
}
]
}
}
]
}
},
"signing_keys": [
{
"kid": "business_2025",
"kty": "EC",
"crv": "P-256",
"x": "WbbXwVYGdJoP4Xm3qCkGvBRcRvKtEfXDbWvPzpPS8LA",
"y": "sP4jHHxYqC89HBo8TjrtVOAGHfJDflYxw7MFMxuFMPY",
"use": "sig",
"alg": "ES256"
}
]
}
The ucp object contains protocol metadata: version, services, and capabilities.
Payment configuration is a sibling — see Payment Architecture. The signing_keys array contains public keys (JWK format) used to verify
signatures on webhooks and other authenticated messages from your servers.