Payments API: Convert any token to USDC

Jupiter supports the payments use case. You can use Jupiter + SolanaPay to pay for anything with any SPL token. With this, you can specify an exact output token amount.

Use Case

Payments or interaction with a protocol can require an exact amount of token B. Users might not have token A or prefer to hold other tokens long term. The Jupiter API allow building a swap transaction to receive an exact amount of token A for a maximum in amount of token B.

A Practical Example using the API

Bob is selling a delicious latte for 5 USDC, Alice only holds mSOL but Bob can use the Jupiter API to let Alice swap for exactly 5 USDC then transfer 5 USDC to his payment wallet.

First, we need to show Alice how much mSOL will he have to spend for the latte.

curl -s 'https://quote-api.jup.ag/v4/quote?inputMint=mSoLzYCxHdYgdzU16g5QSh3i5K3z3KZK7ytfqcJm7So&outputMint=EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v&amount=5000000&swapMode=ExactOut&slippageBps=1' | jq '.data | .[0] | .inAmount, .otherAmountThreshold'

Parameters:

• The input mint is mSOL and the output mint is USDC.
• swapMode is ExactOut, as opposed to the default ExactIn.
• we want to receive amount=5000000, 5 USDC.

Response:

• inAmount is the quoted estimated amount of mSOL required to receive 5 USDC.
• otherAmountThreshold is the maximum in amount, the quote above with the slippage tolerance.

info

Currently, only Orca Whirlpool, Raydium CPAMM, and Raydium CLAMM support ExactOut mode. All tokens may not be available in this mode.

Then Bob creates the transaction with the /swap endpoint, and adds a 5 USDC token transfer from Alice to his payment wallet using the destinationWallet argument, which Alice will verify, sign and send.

info

In the example bellow, we assume the associated token account exists on destinationWallet.

import { Token, TOKEN_PROGRAM_ID, ASSOCIATED_TOKEN_PROGRAM_ID } from '@solana/spl-token'; // version 0.1.x
import { PublicKey } from '@solana/web3.js';

const USDC_MINT = new PublicKey('EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v');
const paymentAmount = 5_000_000; // 5 USDC
const merchantWallet = new PublicKey('BUX7s2ef2htTGb2KKoPHWkmzxPj4nTWMWRgs5CSbQxf9');

// get serialized transactions for the swap
const transactions = await (
  await fetch('https://quote-api.jup.ag/v4/swap', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      // route from /quote api
      route: routes[0],
      userPublicKey: wallet.publicKey.toString(),
    })
  })
).json();

const { swapTransaction } = transactions;

const userDestinationTokenAccount = Token.getAssociatedTokenAddress(
  ASSOCIATED_TOKEN_PROGRAM_ID,
  TOKEN_PROGRAM_ID,
  USDC_MINT,
  wallet.publicKey,
);
const merchantTokenAccount = Token.getAssociatedTokenAddress(
  ASSOCIATED_TOKEN_PROGRAM_ID,
  TOKEN_PROGRAM_ID,
  USDC_MINT,
  merchantWallet,
  // @ts-ignore
  true,
);

// deserialize the transaction
const swapTransactionBuf = Buffer.from(swapTransaction, 'base64');
var transaction = VersionedTransaction.deserialize(swapTransactionBuf);
console.log(transaction);

// get address lookup table accounts
const addressLookupTableAccounts = await Promise.all(
  transaction.message.addressTableLookups.map(async (lookup) => {
    return new AddressLookupTableAccount({
      key: lookup.accountKey,
      state: AddressLookupTableAccount.deserialize(await connection.getAccountInfo(lookup.accountKey).then((res) => res.data)),
    });
  });
);
// console.log(addressLookupTableAccounts)

// decompile transaction message and add transfer instruction
var message = TransactionMessage.decompile(transaction.message,{addressLookupTableAccounts: addressLookupTableAccounts});
message.instructions.push(
  Token.createTransferInstruction(
    TOKEN_PROGRAM_ID,
    userDestinationTokenAccount,
    merchantTokenAccount,
    wallet.publicKey,
    [],
    paymentAmount,
  ),
);

// compile the message and update the transaction
transaction.message = message.compileToV0Message(addressLookupTableAccounts);

// ...Send to Alice to sign then send the transaction

tip

If you want to add your own fees, check out: Adding Your Own Fees