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Paying from a wallet or an exchange

Why the checkout asks for an exact amount, how exchange withdrawals with round amounts are handled, and what to tell customers.

Why the amount has extra decimals

Blockchains like Polygon or Ethereum have no field for an order number. To tell payments apart, every order adds a tiny random amount to the price, for example 10.000123 USDC instead of 10 USDC. NervixPay finds the payment by that exact amount arriving at your address on the chosen network.

Scanning the QR fills in the exact amount and recipient for Polygon, Ethereum and BNB Chain. The customer only approves. This always matches.

From an exchange

Many exchanges round withdrawal amounts or do not allow many decimals. NervixPay therefore also accepts the round price (for example exactly 10 USDC) on Polygon, Ethereum and BNB Chain, but only when that transfer can belong to exactly one open order: same receiving address, network, coin and price.

  • If two customers are paying the same price to you on the same network at the same moment, a round-amount transfer is ambiguous. It is not matched automatically, because guessing could credit the wrong customer. The money is still in your wallet; match it by hand from the transaction.
  • The amount that arrives must equal the exact amount or the round price. If the exchange deducts its withdrawal fee from the amount, the customer must add the fee on top so the full amount arrives.
  • The customer must withdraw on the same network the checkout shows (for example Polygon, not Ethereum).
  • The transfer has to land on-chain before the checkout countdown ends. Some exchanges hold withdrawals for several minutes, so customers paying from an exchange should withdraw right away; see timing.

Wrong amount or wrong network

A transfer with a different amount, or on another network, is not matched to the order. Because NervixPay is non-custodial, the funds are already in your wallet (if they were sent to your address on a network you own). Resolve it with the customer directly: refund from your wallet or ask them to pay the difference. More in troubleshooting.

Paying from a wallet or an exchange | NervixPay Docs