Paper wallets generator. Gift cards. (Warning: wallets.json is overwritten in every run and creates new wallets. Be carefull and save it before the next run)

split-into-wallets.js

// 100,000,000 satoshi = 1 btc
// 100,000 satoshi = 0.001 btc = 1e5

const bitcoin = require('bitcoinjs-lib');
const network = bitcoin.networks.bitcoin;
const blockchainInfoNetwork = network === bitcoin.networks.bitcoin ? 0 : 3; // bitcoin or testnet
const blockexplorer = require('blockchain.info/blockexplorer').usingNetwork(blockchainInfoNetwork); 
const pushtx = require('blockchain.info/pushtx').usingNetwork(blockchainInfoNetwork);

const sourceWIF = ''; // put private key here
const sourceWallet = bitcoin.ECPair.fromWIF(sourceWIF, network);
const sourceAddr = sourceWallet.getAddress();
const wallets = [];
for (let i = 0; i < 400; i++) {
  wallets.push(bitcoin.ECPair.makeRandom({ network }));
}

require('fs').writeFile("./wallets.json", JSON.stringify(wallets.map(w => w.toWIF())), (err) => {
  if (!err) {
    console.log('wallets.json saved');
  } else {
    console.log('Cannot save wallets.json');
  }
});

const amount = 1e5; // 1mBTC
const fee = 6e5;
const amountNeeded = wallets.length * amount + fee;
let transactionAmount = 0;

blockexplorer.getAddress(sourceAddr).then(res => {
  var txb = new bitcoin.TransactionBuilder(network);
  let inputSize = 0;
  let index = 0;
  while (transactionAmount < amountNeeded && index < res.txs.length) {
    let tx = res.txs[index++];
    let out = tx.out.find(o => o.addr === sourceAddr);
    if (out.spent) {
      continue;
    }
    console.log(`addIput(${tx.hash}, ${out.n}) => amount ${out.value}`);
    txb.addInput(tx.hash, out.n);
    transactionAmount += out.value;
    inputSize++;
  }
  
  if (transactionAmount < amountNeeded) {
    console.log(`ERROR: Not enought amount!\navailable${transactionAmount}\nneeded: ${amountNeeded}`);
    return;
  }
  wallets.forEach(w => {
    txb.addOutput(w.getAddress(), amount);
  });
  txb.addOutput(sourceAddr, transactionAmount - amountNeeded); // transfer the rest of the transaction to the original wallet

  for (let i = 0; i < inputSize; i++) {
    txb.sign(i, sourceWallet);
  }

  var tx = txb.build();
  console.log('length: ', tx.toHex().length / 2);
  // console.log(tx.toHex());

  pushtx.pushtx(tx.toHex()).then(res => {
    console.log('TRANSFER Complete', res);
  });
});