Validates a buyer's payment against your requirements without moving any money. It decodes the buyer's signed transaction, screens both the payer and your payee address against Chainalysis, checks the amount / mint / recipient / fee-payer match what you asked for, and simulates the transaction. Call this before you hand over the protected resource — it's your "is this payment going to work?" check.

Response 200 OK — payment is valid

{ "isValid": true, "payer": "BuyerWalletAddress…" }

Response 200 OK — payment is rejected (still HTTP 200)

{ "isValid": false, "invalidReason": "invalid_exact_svm_payload_amount_mismatch", "payer": "BuyerWalletAddress…" }

Field	Type	Description
`isValid`	boolean	`true` only if the payment passed screening, requirement checks, and simulation.
`invalidReason`	string	Present when `isValid` is `false`. Machine-readable code (see Reason codes).
`invalidMessage`	string	(optional) Human-readable elaboration on `invalidReason`.
`payer`	string	The buyer's wallet address, when it could be extracted from the transaction.

Response 400 Bad Request — malformed request (missing a top-level field)

{ "error": { "code": "invalid_request", "message": "missing paymentPayload or paymentRequirements", "request_id": "…" } }

Error reason codes (non-exhaustive)

Code	Meaning
`sanctioned_address`	Payer or payee flagged by Chainalysis screening.
`screener_unavailable`	Screening provider errored and the facilitator is fail-closed. Retry later.
`fee_payer_not_managed_by_facilitator`	The `extra.feePayer` isn't one of our signers — wrong/stale value from `/supported`.
`invalid_exact_svm_payload_amount_mismatch`	Transaction transfers a different amount than `paymentRequirements.amount`.
`invalid_exact_svm_payload_mint_mismatch`	Transaction uses a different token mint than `asset`.
`invalid_exact_svm_payload_recipient_mismatch`	Transaction pays a different recipient than `payTo`.
`network_mismatch`	Payload network doesn't match requirements.
`transaction_simulation_failed`	The transfer would fail on-chain (e.g. insufficient buyer balance).
`unsupported_scheme`	Scheme isn't registered on this facilitator.
`unexpected_verify_error`	Unhandled internal error.

200Verification result (valid or invalid).

400Malformed request body.