Bitcoin Name System (BNS)

Register your domain

git clone

cd smart-contract-examples

npm installnpx hardhat compilenpx hardhat register --domain yourname.btc 

--contract 0x9c40182CE3C2B3f9eE196F43930476E79570826--privatekey 0xafafafafafafafafafafafafafafafafafafafafafafafafafafafafafafafaf 
#your private key

This will output the transaction hash, which can be used to track its status via the 

After it is confirmed, you can try resolving that name by calling the BNS contractnpx hardhat resolve --domain yourname.btc --contract 0x9c40182CE3C2B3f9eE196F43930476E79570826 

Let's build the Bitcoin Name System (BNS), a decentralized, open, and permissionless naming system on Bitcoin.

  • buy and sell BNS name

  • register a human-readable name like 'kevin.bit' or 'bob.btc'

  • map a human-readable name like 'jill.btc' to a machine-readable id like a Bitcoin address

Write the BNS smart contract

It turns out that writing the Bitcoin Name System smart contract is very simple. Here is a basic contract to provide a DNS-like naming system on BitcoinEVM.

// SPDX-License-Identifier: MIT 
Progama solidity ^0.8.0;​import "@openzeppelin/contracts/token/ERC721/ERC721.sol";import "@openzeppelin/contracts/utils/Counters.sol";​contract BNS is ERC721 {​using Counters for Counters.Counter;Counters.Counter private _tokenIds;​mapping(bytes => uint256) public registry;mapping(bytes => bool) public registered;​mapping(uint256 => address) public resolver;​constructor() ERC721("Bitcoin Name System", "BNS") {}​function register(address owner, bytes memory name)publicreturns (uint256){require(!registered[name]);​uint256 id = _tokenIds.current();_mint(owner, id);registry[name] = id;registered[name] = true;resolver[id] = owner;​_tokenIds.increment();return id;}​function map(uint256 tokenId, address to) public {require(msg.sender == ownerOf(tokenId));resolver[tokenId] = to;}}

Extending ERC-721, we only need to implement the register() function to register a new name as an NFT and the map() function to map a human-readable name like 'bob.sat' to a machine-readable id like a wallet address.Sending and receiving a BNS name is now as simple as sending and receiving an NFT. You can also trade the BNS name on open markets since it's an ERC-721.

Clone the smart contract examples

We've prepared a few different examples for you to get started. The BNS example is located at smart-contract-examples/contracts/BNS.sol.git clone​

Compile the contracts

To compile your contracts, use the built-in hardhat compile smart-contract-examplesnpm installnpx hardhat compile​

Deploy the contracts

Review config file hardhat.config.ts. The network configs should look like this.networks:

 {mynw: {url: "http://localhost:10002",accounts: {mnemonic: "<your mnemonic with funds>"},timeout: 100_000,},blockscoutVerify: {blockscoutURL: "http://localhost:4000", // your explorer URL...}}Run the deploy scripts using hardhat-deploy.npx hardhat deploy --tags BNS

Make sure the accounts in hardhat.config.ts have some BTC.​

Interact with the contracts

Once the contracts are deployed, you can interact with them. We've prepared a few hardhat tasks to make it easy for you to interact with the contracts.


a namenpx hardhat register --domain "jill.btc"

#create a mapping 
npx hardhat map "jill.btc" <a-wallet-address>


a human-readable name to a machine-readable idnpx hardhat resolve --domain "jill.btc"

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