Transfer existing NFT tokens via Alchemy Web3 library

NFT
1

I created some NFT tokens through OpenSea on the Polygon Mumbai testnet. Now I need to move these NFTs to different wallet addresses using the Alchemy Web3 library. My application runs on a Node.js backend API without browser wallet integration, so I have to sign transactions manually with a private key.

async function transferNFT() {
  const dotenv = require('dotenv');
  dotenv.config();
  const { ALCHEMY_ENDPOINT, WALLET_PRIVATE_KEY } = process.env;
  const { createAlchemyWeb3 } = require("@alch/alchemy-web3");
  const alchemyWeb3 = createAlchemyWeb3(ALCHEMY_ENDPOINT);
  
  const senderAddress = '*************************'
  const currentNonce = await alchemyWeb3.eth.getTransactionCount(senderAddress, 'latest');
  
  const txData = { // I think this transaction structure is wrong
      'nftAsset': {
        'id': '******************************', // NFT ID from opensea
      },
      'gasLimit': 53000,
      'recipient': '***********************', // destination wallet address
      'amount': 1,
      'nonce': currentNonce,
  }
 
  const signedTransaction = await alchemyWeb3.eth.accounts.signTransaction(txData, WALLET_PRIVATE_KEY);
  alchemyWeb3.eth.sendSignedTransaction(signedTransaction.rawTransaction, function(err, txHash) {
    if (!err) {
      console.log("✅ Transaction hash: ", txHash);
    } else {
      console.log("❌ Transaction failed:", err)
    }
  });
}
transferNFT();

I suspect my transaction object format is incorrect but I’m not sure what the proper structure should be for NFT transfers.

2

hmm, this is interesting! i’ve been messing around with nft transfers on polygon mumbai too recently. one thing that caught my eye - are you sure you’re getting the right contract address for your nft? when you mint through opensea, the actual contract address might be different from what you expect.

have you tried checking the transaction details of your original mint on polygonscan? that should show you the exact contract address and token ID. also, i’m curious - what error messages are you getting when this fails? that could give us a clue about whats going wrong.

another thing to consider is the gas estimation. polygon can be tricky with gas limits, especially for nft transfers. instead of hardcoding 53000, maybe try using estimateGas() first to see what the network thinks you need?

also just wondering - are these nfts you minted yourself or did you buy them from someone else? because if they’re not in your wallet anymore, the transfer will obviously fail. and double check that the token ID format is correct - sometimes opensea shows different IDs than what’s actually on-chain.

what does your alchemy dashboard show when you try to send these transactions? any specific error codes there?

3

yeah the transaction format is definitly wrong there. you cant just send nft transfers like regular eth transactions - you gotta call the smart contract methods properly. also make sure youre using the actual contract address from the nft collection, not openseas proxy address which sometimes shows up in their api responses.

4

Your transaction structure is indeed incorrect. NFT transfers require calling the contract’s transfer function directly, not using a custom transaction format. You need to interact with the ERC-721 contract using its ABI and call either transferFrom or safeTransferFrom method.

Here’s the corrected approach:

const contractABI = [...]; // ERC-721 ABI
const contractAddress = 'your_nft_contract_address';
const contract = new alchemyWeb3.eth.Contract(contractABI, contractAddress);

const txData = {
  from: senderAddress,
  to: contractAddress,
  gas: 100000,
  gasPrice: await alchemyWeb3.eth.getGasPrice(),
  nonce: currentNonce,
  data: contract.methods.transferFrom(senderAddress, recipientAddress, tokenId).encodeABI()
};

Make sure you have the contract address (not just the token ID) and the proper ERC-721 ABI. The gas limit should also be higher than 53000 for NFT transfers.