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Every paid call through the gateway settles in USDC on Solana mainnet through a standard x402 facilitator. Tokens API routes do not settle on-chain; they authenticate with a wallet signature and no funds move. This page describes what settlement means for you as a client. If you want the mechanics of the x402 wire format, see Access modes and the Payment headers reference.

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The guarantee

You pay only for successful calls. For every paid request, the gateway performs the following sequence:
  1. Verify - the PAYMENT-SIGNATURE you attach is checked against the advertised price, network, and recipient.
  2. Call upstream - the gateway forwards your validated request to the underlying provider (Alchemy, Helius).
  3. Settle on success - only if the upstream returned a successful response, the gateway submits your pre-signed transfer on-chain.
If anything in steps 1 or 2 fails, verification error, provider outage, malformed upstream reply, the gateway discards the payment authorization and no USDC moves. You can retry safely; each attempt produces a new single-use payment.

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What you see back

On a successful paid request, the gateway returns the upstream’s JSON response plus an X-PAYMENT-RESPONSE header containing a proof of settlement: 
{
  "success": true,
  "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
  "transaction": "<Solana transaction hash>",
  "payer": "<your wallet pubkey>",
  "settledAt": "2026-04-18T11:32:00Z"
}
The transaction field is a standard Solana signature you can look up in any explorer. It is the canonical record that this call was paid for. SIWX (Tokens API) responses never include this header because nothing is settled on-chain.

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Non-custodial by design

  • The gateway never holds your funds. Your PAYMENT-SIGNATURE is a transfer you signed directly from your own wallet; settlement submits that transfer as-is.
  • The gateway never requests or stores your private keys.
  • The gateway cannot settle a payment for more than the price advertised in the original 402 challenge.

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Replay protection

Each PAYMENT-SIGNATURE authorizes exactly one call. Submitting the same payment twice returns 400 Bad Request, the second call is not settled. This is enforced before the upstream call, so there is no way a paid request can be charged twice.

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See also