OPNet - Smart Contracts on Bitcoin L1

The official client library for building Bitcoin-based applications on OPNet. Full TypeScript support with type-safe contract interactions.

Security Audit

This library has been professionally audited by Verichains.

See SECURITY.md for details.

Installation

npm install opnet @btc-vision/transaction @btc-vision/bitcoin

Documentation

Check out the full documentation in /docs!

• Getting Started
• Providers - JSON-RPC & WebSocket connections
• Smart Contracts - Contract interactions & transactions
• UTXO Management - Bitcoin UTXO handling
• Offline Signing - Cold wallet support
• ABI Reference - OP20, OP721, MotoSwap ABIs
• API Reference - Full API documentation

RPC Endpoints

| Network | URL | |---------|-----------------------------| | Mainnet | https://mainnet.opnet.org | | Testnet | https://testnet.opnet.org | | Regtest | https://regtest.opnet.org |

Quick Start

import { BitcoinUtils, getContract, IOP20Contract, JSONRpcProvider, OP_20_ABI } from 'opnet';
import { AddressTypes, Mnemonic, MLDSASecurityLevel } from '@btc-vision/transaction';
import { networks } from '@btc-vision/bitcoin';

// Connect to OPNet
const provider = new JSONRpcProvider('https://testnet.opnet.org', networks.
opnetTestnet);

// Create wallet from mnemonic
const mnemonic = new Mnemonic(
    'your twenty four word seed phrase goes here ...',
    '',
    networks.opnetTestnet,
    MLDSASecurityLevel.LEVEL2,
);
const wallet = mnemonic.deriveOPWallet(AddressTypes.P2TR, 0);
const myAddress = wallet.address;

// Interact with a token contract
const token = getContract<IOP20Contract>(
    'op1...', // contract address
    OP_20_ABI,
    provider,
    networks.opnetTestnet,
    myAddress
);

// Read token info
const name = await token.name();
const balance = await token.balanceOf(myAddress);

console.log('Token:', name.properties.name);
console.log('Balance:', balance.properties.balance);

// Send a transaction (100 tokens with 8 decimals)
const amount = BitcoinUtils.expandToDecimals(100, 8);
const simulation = await token.transfer(recipientAddress, amount);

if (simulation.revert) {
    throw new Error(`Transfer would fail: ${simulation.revert}`);
}

const tx = await simulation.sendTransaction({
    signer: wallet.keypair,
    mldsaSigner: wallet.mldsaKeypair,
    refundTo: wallet.p2tr,
    maximumAllowedSatToSpend: 50000n,
    feeRate: 10,
    network: networks.opnetTestnet,
});

console.log('TX ID:', tx.transactionId);

Requirements

• Node.js >= 24.0.0
• TypeScript >= 5.9

Development

git clone https://github.com/btc-vision/opnet.git
cd opnet
npm install
npm run build

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Run tests: npm test
5. Submit a pull request

See the pull request template for requirements.

Reporting Issues

• Bugs: Use the bug report template
• Security: See SECURITY.md - do not open public issues for vulnerabilities

License

Apache-2.0

Links

• OPNet
• Documentation
• GitHub
• npm
• Verichains