Documentation Index Fetch the complete documentation index at: https://developers.fd.xyz/llms.txt
Use this file to discover all available pages before exploring further.
Reference for each Prism Gateway API endpoint. See Introduction for base URLs, authentication, and error handling.
All authenticated endpoints require the X-Project-Identify-Token header. Request and response bodies are JSON.
x402 Settlement Facilitator endpoints for the x402 payment flow. The server-side SDKs call these automatically. Use them directly for custom integrations.
Get Payment Requirements Generate x402 payment requirements for a resource. Returns the accepted payment methods, token amounts, and settlement addresses.
POST /api/v2/payment/requirements
Request Body Field Type Required Description resourceUrlstring Yes URL of the protected resource requestedAmountnumber Yes Amount to charge (in the resource’s currency) descriptionstring No Human-readable description of the resource mimeTypestring No MIME type of the resource content
curl -X POST https://prism-gw.fd.xyz/api/v2/payment/requirements \ -H "X-Project-Identify-Token: your-project-identify-token" \ -H "Content-Type: application/json" \ -d '{ "resourceUrl": "https://api.example.com/premium/data", "requestedAmount": 0.50, "description": "Premium API access" }'
Response (PaymentRequiredResponse){ "x402Version" : 2 , "resource" : { "url" : "https://api.example.com/premium/data" , "description" : "Premium API access" }, "accepts" : [ { "scheme" : "exact" , "network" : "base" , "amount" : "500000" , "payTo" : "0x1234...abcd" , "maxTimeoutSeconds" : 300 , "asset" : "0xUSDC...addr" , "extra" : null , "protocolVersion" : 2 } ], "protocolVersion" : 2 }
The accepts array contains one entry per token/chain combination the merchant supports. Clients pick one and construct a signed authorization against it.
Verify Payment Verify a signed x402 payment authorization without settling it on-chain.
POST /api/v2/payment/verify
Request Body (PaymentSubmissionRequest2)Field Type Required Description paymentPayloadobject Yes Signed payment authorization (see below) paymentRequirementsobject Yes The accepted payment requirement this authorization targets
Show paymentPayload fields
Field Type Required Description x402Versioninteger Yes Protocol version (2) acceptedobject Yes The accepts entry the payer selected payloadobject Yes Signed authorization data (scheme-specific) resourceobject No Resource metadata extensionsobject No Protocol extensions
Show paymentRequirements fields
Field Type Required Description schemestring Yes Payment scheme (e.g. "exact") networkstring Yes Chain identifier (e.g. "base") amountstring Yes Token amount in smallest unit payTostring Yes Merchant settlement address maxTimeoutSecondsinteger Yes Max time before authorization expires assetstring Yes Token contract address
Response (VerifyResponse2){ "isValid" : true , "payer" : "0xPayerAddress...1234" }
Field Type Description isValidboolean Whether the authorization is valid payerstring Payer wallet address (if valid) invalidReasonstring Reason for rejection (if invalid)
Settle Payment Settle a verified payment on-chain. Executes the transferWithAuthorization (ERC-3009) call to move tokens from the payer to the merchant.
POST /api/v2/payment/settle
Request Body (PaymentSubmissionRequest2)Same structure as Verify Payment .
Response (SettleResponse){ "success" : true , "payer" : "0xPayerAddress...1234" , "transaction" : "0xTransactionHash...abcd" , "network" : "base" }
Field Type Description successboolean Whether settlement succeeded payerstring Payer wallet address transactionstring On-chain transaction hash networkstring Chain the settlement executed on errorReasonstring Reason for failure (if unsuccessful)
Returns 502 Bad Gateway with a ProblemDetails body if the on-chain transaction fails.
Merchant Endpoints for UCP merchants to build discovery profiles and prepare checkout sessions.
Get Payment Profile Returns the payment_handlers block for your UCP discovery profile. Include this in your storefront’s UCP profile so agents can discover your supported payment methods.
GET /api/v2/merchant/payment-profile
curl https://prism-gw.fd.xyz/api/v2/merchant/payment-profile \ -H "X-Project-Identify-Token: your-project-identify-token"
Response (PaymentProfileResponse){ "xyz.fd.prism_payment" : [ { "id" : "xyz.fd.prism_payment" , "version" : "2026-01-23" } ] }
Returns 404 if the merchant is not configured in Prism Console.
Prepare Checkout Convert a fiat amount into x402 payment handler entries with resolved token amounts. Use this when a buyer selects items and you need to build the checkout payment_handlers block with concrete token prices.
POST /api/v2/merchant/checkout-prepare
Request Body Field Type Required Description amountstring Yes Fiat amount (e.g. "10.00") currencystring Yes Fiat currency code (e.g. "USD") resourceobject Yes Resource being purchased resource.urlstring Yes URL identifying the resource resource.descriptionstring No Human-readable description
curl -X POST https://prism-gw.fd.xyz/api/v2/merchant/checkout-prepare \ -H "X-Project-Identify-Token: your-project-identify-token" \ -H "Content-Type: application/json" \ -d '{ "amount": "10.00", "currency": "USD", "resource": { "url": "https://shop.example.com/order/12345", "description": "Order #12345" } }'
Response (CheckoutPrepareResponse){ "xyz.fd.prism_payment" : [ { "id" : "xyz.fd.prism_payment" , "version" : "2026-01-23" , "config" : { "x402Version" : 2 , "resource" : { "url" : "https://shop.example.com/order/12345" , "description" : "Order #12345" }, "accepts" : [ { "scheme" : "exact" , "network" : "base" , "payTo" : "0xMerchant...addr" , "maxTimeoutSeconds" : 300 , "asset" : "0xUSDC...addr" , "amount" : "10000000" }, { "scheme" : "exact" , "network" : "base" , "payTo" : "0xMerchant...addr" , "maxTimeoutSeconds" : 300 , "asset" : "0xFDUSD...addr" , "amount" : "10000000" } ] } } ] }
The response contains one accepts entry per token/chain combination the merchant supports, with amount resolved from the fiat price. Include this in your UCP checkout response so agents can select a payment option and authorize the transfer.
Returns 404 if the merchant is not configured in Prism Console.
Gateway Public endpoints serving the UCP handler reference. No authentication required.
Handler Schema Returns the JSON schema for the xyz.fd.prism_payment handler.
curl https://prism-gw.fd.xyz/ucp/schema.json
Handler Specification Returns the human-readable specification for the xyz.fd.prism_payment handler in Markdown format.
curl https://prism-gw.fd.xyz/ucp/prism.md
