BRC-721: NFTs

The BRC-721 token standard on Bitcoin is similar to ERC-721 on Ethereum. It can represent virtually anything in Bitcoin:

• collectible items

• memberships

• lottery tickets

• in-game items

• and more

Write a BRC-721 smart contract

Extending the OpenZeppelin ERC-721 contract, we can create a hypothetical PFP NFT collection (CryptoWizards) on Bitcoin.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";

contract CryptoWizards is ERC721URIStorage {
 
    constructor() ERC721("CryptoWizards", "WIZ") {}

    function safeMint(address to, uint256 tokenId, string memory uri) public {
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
    }
}

Compile the contracts

To compile your contracts, use the built-in hardhat compile task.

cd smart-contract-examples
npm install
npx 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 NFT

Make sure the accounts in hardhat.config.ts have some TC.

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.

# ./CryptoWizards/wizard100.jpg
npx hardhat mint-nft --metadata wizard100.json --tokenid 100

# output should contain the URI
npx hardhat get-nft --uri bfs://22213/0xfe94d57c6ef567d26e3524f54dc2772329092ffd/0xd3b0932Dff95a56c6024328162a3040F5e717F76/100