Simulate a transfer

For testing: make a crypto checkout receive its transfer now, exact or not.

For testing, on a simulated business only. Nothing watches a chain there, so an open crypto checkout receives its transfer 20 seconds after it opens. This makes the transfer arrive now, the way simulate says, and returns the checkout as it left it. Public, like the rest of a checkout. A live business watches the chain for real transfers instead.

On an underpaid checkout, the transfer is measured against what's still due, so exact sends the rest. A checkout that's already confirming, completed or in needs_review comes back as it is, with no second transfer.

Path

id string Required

The checkout's ID, such as chk_C5yhPQvPqpYgdDgj.

Body

simulate string

How the transfer arrives. Defaults to exact, whatever the checkout was created with. underpaid sends 90% and overpaid 110%. wrong_network arrives on another EVM network at the same address, so it needs a coin both carry, such as USDC, and late ends the quote first, if it hasn't ended, so the transfer comes after expiry. Both put the checkout in needs_review. See testing.

Errors

400 invalid_request

simulate isn't one it takes, or it's wrong_network on a network outside the EVM family or in a coin no other EVM network carries.
404 not_found

No checkout has that ID.
409 wrong_rail

The checkout is for a card, which finishes on the secure payment page.
409 checkout_canceled

The checkout was canceled.
409 checkout_failed

The checkout failed.
410 checkout_expired

The quote expired, and simulate isn't late.

Any request can also fail on its key or its body. See errors.

Request

curl -X POST "https://dash.402pay.co/api/v1/checkouts/chk_C5yhPQvPqpYgdDgj/mark-sent" \  -H "Content-Type: application/json" \  -d '{    "simulate": "exact"  }'

Response200 OK

{  "data": {    "id": "chk_C5yhPQvPqpYgdDgj",    "kind": "checkout",    "status": "confirming",    "rail": "crypto",    "link_id": null,    "payment_id": "pmt_QI02vLdJGd48hBbg",    "amount": 4900,    "currency": "USD",    "breakdown": {      "currency": "USD",      "price": 4900,      "processing_fee": null,      "network_fee": 2,      "total": 4902    },    "crypto": {      "asset": "USDC",      "network": "polygon",      "amount": "49.00",      "address": "0x9a3c416D4A81669C01f4515bBDEB93C45d3813fe",      "payment_uri": "ethereum:0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359@137/transfer?address=0x9a3c416D4A81669C01f4515bBDEB93C45d3813fe&uint256=49000000",      "rate": {        "amount": 100,        "currency": "USD"      },      "received_amount": "49.00",      "remaining_amount": null,      "remaining_payment_uri": null,      "overpaid_amount": null,      "detected_network": null,      "tx_hash": "0xc16a611d90302ba917593ed9743f5e734a556e8d2f35bb0d60a2ca02ac99bb20",      "explorer_url": "https://polygonscan.com/tx/0xc16a611d90302ba917593ed9743f5e734a556e8d2f35bb0d60a2ca02ac99bb20"    },    "card": null,    "confirmations": {      "current": 0,      "required": 4    },    "remainder": false,    "canceled_by": null,    "replaced_by": null,    "failure_code": null,    "review_reason": null,    "success_url": "https://example.com/thanks",    "expires_at": "2026-09-26T21:37:47.047Z",    "sent_at": "2026-09-26T21:23:07.047Z",    "created_at": "2026-09-26T21:22:47.047Z",    "updated_at": "2026-09-26T21:23:07.047Z"  }}