Solana Payment Gateway swaping issue

Question

I am developing a payment gateway on Solana and need to swap tokens programmatically using Node.js. Currently, I am testing SOL to USDC swaps with the Jupiter API.

Everything works until generating the transaction signature. However, after that, the swap does not execute—tokens remain the same. I don’t see any errors, but the transaction does not go through.

const {
 Connection,
 Keypair,
 PublicKey,
 clusterApiUrl,
 LAMPORTS_PER_SOL,
 VersionedTransaction,
} = require("@solana/web3.js");
const {
 getAssociatedTokenAddressSync,
 TOKEN_PROGRAM_ID,
 ASSOCIATED_TOKEN_PROGRAM_ID,
} = require("@solana/spl-token");
const fetch = require("node-fetch"); // Ensure you have node-fetch installed
const connection = new Connection(clusterApiUrl("mainnet-beta"), "confirmed");
const swapTokens = async (req, res) => {
 try {
 // **STEP 1: Get Best Quote**
 const inputMint = "So11111111111111111111111111111111111111112"; // SOL
 const outputMint = "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"; // USDC
 const userPublicKey = new PublicKey("YOUR_WALLET_PUBLIC_KEY"); // Replace with actual user public key
 const amount = 0.000010; // Amount in SOL
 const solAmount = Math.floor(amount * 1e9); // Convert SOL to lamports
 const quoteResponse = await (
 await fetch(
 `https://api.jup.ag/swap/v1/quote?inputMint=${inputMint}&outputMint=${outputMint}&amount=${solAmount}&slippageBps=50&restrictIntermediateTokens=true&swapMode=ExactIn`
 )
 ).json();
 console.log("Quote Response:", JSON.stringify(quoteResponse, null, 2));
 // **STEP 2: Execute Swap**
 const swapResponse = await (
 await fetch("https://api.jup.ag/swap/v1/swap", {
 method: "POST",
 headers: {
 "Content-Type": "application/json",
 },
 body: JSON.stringify({
 quoteResponse,
 userPublicKey: userPublicKey.toBase58(),
 }),
 })
 ).json();
 console.log("Swap Response:", swapResponse);
 // **STEP 3: Sign and Send Transaction**
 const transactionBase64 = swapResponse.swapTransaction;
 const transaction = VersionedTransaction.deserialize(Buffer.from(transactionBase64, "base64"));
 
 console.log("Deserialized Transaction:", transaction);
 const mainWallet = Keypair.fromSecretKey(Uint8Array.from(YOUR_SECRET_KEY)); // Replace with your private key
 transaction.sign([mainWallet]);
 const transactionBinary = transaction.serialize();
 console.log("Serialized Transaction:", transactionBinary);
 const signature = await connection.sendRawTransaction(transactionBinary, {
 maxRetries: 2,
 skipPreflight: true,
 });
 console.log("Transaction Signature:", signature);
 const confirmation = await connection.confirmTransaction({ signature }, "finalized");
 
 console.log("Transaction Confirmation:", confirmation);
 if (confirmation.value.err) {
 console.log(`Transaction failed: ${JSON.stringify(confirmation.value.err)}\nhttps://solscan.io/tx/${signature}/`);
 } else {
 console.log(`Transaction successful: https://solscan.io/tx/${signature}/`);
 }
 res.status(200).json({ message: "Swap executed successfully", signature });
 } catch (error) {
 console.error("Swap Error:", error);
 res.status(500).json({ message: "Swap failed: " + error.message });
 }
};

Answer 1

Pass quoteResponse.quote instead of full quoteResponse and Enable preflight to ensure transaction executes properly

const swapTokens = async (req, res) => {
 try {
 const inputMint = "So11111111111111111111111111111111111111112"; // SOL
 const outputMint = "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"; // USDC
 const userPublicKey = new PublicKey("YOUR_WALLET_PUBLIC_KEY"); // Replace
 const amount = 0.000010;
 const solAmount = Math.floor(amount * 1e9);
 const quoteResponse = await (
 await fetch(
 `https://api.jup.ag/swap/v1/quote?inputMint=${inputMint}&outputMint=${outputMint}&amount=${solAmount}&slippageBps=50`
 )
 ).json();
 console.log("Quote Response:", quoteResponse);
 // **Extract only `quoteResponse.quote`**
 const swapResponse = await (
 await fetch("https://api.jup.ag/swap/v1/swap", {
 method: "POST",
 headers: { "Content-Type": "application/json" },
 body: JSON.stringify({
 quoteResponse: quoteResponse.quote, // Only pass `quote`
 userPublicKey: userPublicKey.toBase58(),
 }),
 })
 ).json();
 console.log("Swap Response:", swapResponse);
 // Deserialize transaction
 const transactionBase64 = swapResponse.swapTransaction;
 const transaction = VersionedTransaction.deserialize(Buffer.from(transactionBase64, "base64"));
 console.log("Deserialized Transaction:", transaction);
 // Sign with the main wallet
 const mainWallet = Keypair.fromSecretKey(Uint8Array.from(YOUR_SECRET_KEY)); // Replace
 transaction.sign([mainWallet]);
 // Convert to binary
 const transactionBinary = Buffer.from(transaction.serialize());
 // Send transaction
 const signature = await connection.sendRawTransaction(transactionBinary, {
 maxRetries: 2,
 skipPreflight: false, // Ensure preflight checks
 });
 console.log("Transaction Signature:", signature);
 // Confirm transaction
 const confirmation = await connection.confirmTransaction(signature, "confirmed");
 if (confirmation.value.err) {
 console.log(`Transaction failed: https://solscan.io/tx/${signature}`);
 } else {
 console.log(`Transaction successful: https://solscan.io/tx/${signature}`);
 }
 res.status(200).json({ message: "Swap executed successfully", signature });
 } catch (error) {
 console.error("Swap Error:", error);
 res.status(500).json({ message: "Swap failed: " + error.message });
 }
};