Bitcoin Basics: Getting Started with Bitcoin Integration

This guide covers how to use the VerifiedX Web SDK for Bitcoin operations. The SDK provides a comprehensive Bitcoin client that supports wallet management, transactions, and mempool interactions through the Mempool.space API.

Prerequisites

• Node.js 20+ or a modern browser
• Basic understanding of Bitcoin concepts
• vfx-web-sdk installed in your project

Understanding Bitcoin Networks

The SDK supports both Bitcoin networks:

• Mainnet: The production Bitcoin network with real BTC
• Testnet: The test network with test BTC (recommended for development)

Step 1: Initialize the Bitcoin Client

The BtcClient provides all Bitcoin functionality in a single interface:

import { btc } from 'vfx-web-sdk';

// Initialize for testnet (recommended for development)
const client = new btc.BtcClient('testnet');

// For mainnet (production)
// const client = new btc.BtcClient('mainnet');

Step 2: Generate Bitcoin Wallets

The SDK supports multiple ways to create Bitcoin wallets:

Method 1: Generate Random Wallet

// Generate a completely random wallet
const keypair = client.generatePrivateKey();

console.log('Bitcoin Addresses:');
console.log('- Legacy (P2PKH):', keypair.addresses.p2pkh);
console.log('- Nested SegWit (P2SH):', keypair.addresses.p2sh);
console.log('- Native SegWit (Bech32):', keypair.addresses.bech32);
console.log('- Taproot (Bech32m):', keypair.addresses.bech32m);
console.log('- Default Address:', keypair.address);
console.log('- WIF:', keypair.wif);

Method 2: Generate from Mnemonic

// Generate wallet with mnemonic for recovery
const mnemonicWallet = client.generateMnemonic();

console.log('Mnemonic Wallet:');
console.log('- Mnemonic:', mnemonicWallet.mnemonic);
console.log('- Address:', mnemonicWallet.address);
console.log('- WIF:', mnemonicWallet.wif);

Method 3: Restore from Mnemonic

// Restore an existing wallet from mnemonic
const restoredWallet = client.privateKeyFromMnemonic(
  'your twelve word mnemonic phrase goes here like this example',
  0 // account index
);

console.log('Restored wallet address:', restoredWallet.address);

Method 4: Import from WIF or Private Key

// Import from Wallet Import Format (WIF)
const wifWallet = client.addressFromWif('your-wif-string-here');

// Import from private key hex
const privateKeyWallet = client.publicFromPrivate('your-private-key-hex');

Method 5: Email-Based Wallet (Cross-Platform)

For cross-platform compatibility with web wallets:

// Generate deterministic wallet from email/password
const emailWallet = client.generateEmailKeypair(
  'user@example.com',
  'secure-password',
  0 // index
);

console.log('Email-based wallet:', emailWallet.address);

Step 3: Check Account Information

Get detailed information about any Bitcoin address:

async function getAccountInfo(address: string) {
  try {
    const info = await client.getAddressInfo(address);

    console.log('Account Information:');
    console.log('- Balance:', info.balance, 'satoshis');
    console.log('- Balance (BTC):', info.balance / 100000000, 'BTC');
    console.log('- Total Received:', info.totalRecieved, 'satoshis');
    console.log('- Total Sent:', info.totalSent, 'satoshis');
    console.log('- Transaction Count:', info.txCount);

    return info;
  } catch (error) {
    console.error('Error fetching account info:', error.message);
  }
}

// Check your wallet balance
const wallet = client.generatePrivateKey();
await getAccountInfo(wallet.address);

Step 4: Get Transaction History

Retrieve transaction history for any address:

async function getTransactionHistory(address: string) {
  try {
    const transactions = await client.getTransactions(address);

    console.log(`Found ${transactions.length} transactions:`);

    transactions.forEach((tx, index) => {
      console.log(`\nTransaction ${index + 1}:`);
      console.log('- TX ID:', tx.txid);
      console.log('- Confirmed:', tx.status.confirmed);
      console.log('- Block Height:', tx.status.block_height);
      console.log('- Fee:', tx.fee, 'satoshis');
      console.log('- Size:', tx.size, 'bytes');
    });

    return transactions;
  } catch (error) {
    console.error('Error fetching transactions:', error.message);
  }
}

await getTransactionHistory(wallet.address);

Step 5: Check Current Fee Rates

Before sending transactions, check current network fee rates:

async function getCurrentFees() {
  try {
    const fees = await client.getFeeRates();

    if (fees) {
      console.log('Current Fee Rates (sat/vB):');
      console.log('- Fastest (next block):', fees.fastestFee);
      console.log('- Half hour:', fees.halfHourFee);
      console.log('- One hour:', fees.hourFee);
      console.log('- Economy:', fees.economyFee);
      console.log('- Minimum:', fees.minimumFee);
    }

    return fees;
  } catch (error) {
    console.error('Error fetching fees:', error.message);
  }
}

await getCurrentFees();

Step 6: Send Bitcoin Transactions

Simple Send (Recommended)

The easiest way to send Bitcoin:

async function sendBitcoin(senderWif: string, recipientAddress: string, amountSats: number) {
  try {
    console.log(`Sending ${amountSats} satoshis to ${recipientAddress}`);

    // This method handles transaction creation and broadcasting
    const txId = await client.sendBtc(
      senderWif,
      recipientAddress,
      amountSats,
      20 // fee rate in sat/vB (optional)
    );

    console.log('Transaction sent successfully!');
    console.log('Transaction ID:', txId);

    return txId;
  } catch (error) {
    console.error('Transaction failed:', error.message);
  }
}

// Send 50,000 satoshis (0.0005 BTC)
const wallet = client.generatePrivateKey();
await sendBitcoin(
  wallet.wif,
  'recipient-bitcoin-address',
  50000
);

Advanced Send (Manual Control)

For more control over the transaction process:

async function advancedSend(senderWif: string, recipientAddress: string, amountSats: number) {
  try {
    // Step 1: Create the transaction
    const createResult = await client.createTransaction(
      senderWif,
      recipientAddress,
      amountSats,
      15 // custom fee rate
    );

    if (!createResult.success) {
      console.error('Failed to create transaction:', createResult.error);
      return;
    }

    console.log('Transaction created successfully');
    console.log('Raw transaction:', createResult.result);

    // Step 2: Broadcast the transaction
    const broadcastResult = await client.broadcastTransaction(createResult.result!);

    if (!broadcastResult.success) {
      console.error('Failed to broadcast transaction:', broadcastResult.error);
      return;
    }

    console.log('Transaction broadcast successfully');
    console.log('Transaction ID:', broadcastResult.result);

    return broadcastResult.result;
  } catch (error) {
    console.error('Advanced send failed:', error.message);
  }
}

Step 7: Message Signing

Sign and verify Bitcoin messages:

function signMessage(message: string, wallet: any) {
  try {
    // Sign with WIF
    const signature = client.getSignatureFromWif(message, wallet.wif);
    console.log('Message signature:', signature);

    // Alternative: Sign with private key
    // const signature2 = client.getSignature(message, wallet.privateKey);

    return signature;
  } catch (error) {
    console.error('Signing failed:', error.message);
  }
}

const wallet = client.generatePrivateKey();
const signature = signMessage('Hello, Bitcoin!', wallet);

Complete Example: Bitcoin Wallet Manager

Here’s a comprehensive Bitcoin wallet manager:

import { btc } from 'vfx-web-sdk';

class BitcoinWalletManager {
  private client: btc.BtcClient;

  constructor(network: 'mainnet' | 'testnet' = 'testnet') {
    this.client = new btc.BtcClient(network);
  }

  // Create new wallet
  createWallet() {
    return this.client.generateMnemonic();
  }

  // Restore wallet from mnemonic
  restoreWallet(mnemonic: string, index: number = 0) {
    return this.client.privateKeyFromMnemonic(mnemonic, index);
  }

  // Import wallet from WIF
  importWallet(wif: string) {
    return this.client.addressFromWif(wif);
  }

  // Get wallet balance and info
  async getWalletInfo(address: string) {
    const [accountInfo, transactions] = await Promise.all([
      this.client.getAddressInfo(address),
      this.client.getTransactions(address)
    ]);

    return {
      balance: accountInfo.balance,
      balanceBTC: accountInfo.balance / 100000000,
      totalReceived: accountInfo.totalRecieved,
      totalSent: accountInfo.totalSent,
      transactionCount: accountInfo.txCount,
      recentTransactions: transactions.slice(0, 5) // Last 5 transactions
    };
  }

  // Send Bitcoin
  async sendBitcoin(fromWif: string, toAddress: string, amountSats: number, feeRate?: number) {
    return await this.client.sendBtc(fromWif, toAddress, amountSats, feeRate);
  }

  // Get current network fees
  async getNetworkFees() {
    return await this.client.getFeeRates();
  }

  // Sign a message
  signMessage(message: string, wif: string) {
    return this.client.getSignatureFromWif(message, wif);
  }
}

// Usage example
async function main() {
  const walletManager = new BitcoinWalletManager('testnet');

  // Create a new wallet
  const wallet = walletManager.createWallet();
  console.log('New Bitcoin wallet created:');
  console.log('Mnemonic:', wallet.mnemonic);
  console.log('Address:', wallet.address);
  console.log('All address types:', wallet.addresses);

  // Get wallet information
  try {
    const walletInfo = await walletManager.getWalletInfo(wallet.address);
    console.log('\nWallet Information:');
    console.log('Balance:', walletInfo.balanceBTC, 'BTC');
    console.log('Transactions:', walletInfo.transactionCount);
  } catch (error) {
    console.log('New wallet - no transactions yet');
  }

  // Check network fees
  const fees = await walletManager.getNetworkFees();
  if (fees) {
    console.log('\nCurrent Network Fees:');
    console.log('Fast:', fees.fastestFee, 'sat/vB');
    console.log('Standard:', fees.hourFee, 'sat/vB');
    console.log('Economy:', fees.economyFee, 'sat/vB');
  }

  // Sign a message
  const message = 'Hello from VerifiedX SDK!';
  const signature = walletManager.signMessage(message, wallet.wif);
  console.log('\nMessage Signature:');
  console.log('Message:', message);
  console.log('Signature:', signature);
}

main().catch(console.error);

Address Types Explained

The SDK generates multiple address types for maximum compatibility:

Legacy (P2PKH) - addresses start with ‘1’

• Oldest address format
• Highest fees
• Maximum compatibility

Nested SegWit (P2SH) - addresses start with ‘3’

• Medium fees
• Good compatibility
• Wrapped SegWit transactions

Native SegWit (Bech32) - addresses start with ‘bc1’ (mainnet) or ‘tb1’ (testnet)

• Lower fees
• Modern standard
• Best for most use cases

Taproot (Bech32m) - addresses start with ‘bc1p’ (mainnet) or ‘tb1p’ (testnet)

• Lowest fees
• Latest Bitcoin upgrade
• Advanced privacy features

Best Practices

Security

• Secure WIF storage: WIF keys provide full access to funds
• Use strong passwords: For email-based wallets
• Test on testnet first: Always test with testnet Bitcoin

Performance

• Cache fee rates: Don’t fetch fees for every transaction
• Batch operations: Group multiple API calls when possible
• Handle rate limits: Mempool.space has API rate limits

Error Handling

• Check balances: Ensure sufficient balance before sending
• Validate addresses: Verify recipient addresses
• Monitor confirmations: Track transaction confirmations

What’s Next?

Now that you understand Bitcoin basics:

1. Learn Cross-Chain: Explore Cross-Chain Integration
2. Build Applications: Check out Complete Applications
3. API Reference: Browse the BtcClient API

Common Issues

Insufficient Balance

Make sure your wallet has enough Bitcoin. On testnet, get signet BTC from the testnet faucet (Signet BTC tab).

Transaction Fee Too Low

Increase the fee rate if transactions are stuck in mempool.

Invalid Address Format

Ensure you’re using the correct address format for the recipient’s wallet.

Network Connection Issues

Check internet connection and try again. The SDK automatically retries failed requests.

Getting Help

• Check the BtcClient API Reference
• Browse Bitcoin Examples
• Report issues on GitHub