How to use Hardhat to deploy NFT contracts? (Developer guide)

Setting Up the Hardhat Environment

1. Install Node.js version 16 or higher to ensure compatibility with Hardhat’s latest tooling and plugins.

2. Initialize a new npm project by running npm init -y in an empty directory.

3. Install Hardhat as a development dependency using npm install --save-dev hardhat.

4. Execute npx hardhat and select “Create an empty hardhat.config.js” to generate the base configuration file.

5. Add essential plugins such as @nomicfoundation/hardhat-toolbox for built-in testing utilities and Ethers integration.

Writing an ERC-721 NFT Contract

1. Create a new Solidity file under contracts/MyNFT.sol and import OpenZeppelin’s ERC-721 implementation.

2. Define a contract that inherits from ERC721 and Ownable, assigning a name and symbol during construction.

3. Implement a mint function restricted to the owner, which calls _safeMint to assign tokens to specified addresses.

4. Add a tokenURI override to return dynamic metadata URLs based on token ID, supporting IPFS or centralized endpoints.

5. Include a baseTokenURI state variable and setter function to allow URI prefix updates without redeploying.

Configuring Deployment Scripts

1. Create a deployment script inside scripts/deploy.js that imports the contract artifact and initializes a Hardhat runtime environment.

2. Retrieve the signer using ethers.getSigners()[0] and connect the contract factory to it.

3. Instantiate the contract with constructor arguments including name, symbol, and initial base URI.

4. Wait for transaction confirmation after calling deploy(), then log the deployed contract address.

5. Store the address in a local JSON file or environment variable for later verification or frontend integration.

Deploying to Testnets and Mainnet

1. Configure network settings in hardhat.config.js by adding RPC endpoints for networks like Sepolia or Polygon Mumbai.

2. Securely manage private keys using environment variables via dotenv, never committing them to version control.

3. Use npx hardhat run scripts/deploy.js --network sepolia to initiate deployment with proper gas estimation.

4. Verify the contract source code on Etherscan or Polygonscan using the @nomicfoundation/hardhat-verify plugin.

5. Confirm successful minting by interacting with the deployed contract using Hardhat console or third-party explorers.

Frequently Asked Questions

Q: Can I deploy multiple NFT contracts with different metadata structures using the same Hardhat setup?A: Yes. Each contract can reside in its own Solidity file and be deployed via separate scripts with unique constructor parameters.

Q: What happens if a deployment transaction fails due to insufficient gas on a testnet?A: Hardhat automatically estimates gas limits, but manual overrides via gasLimit in the deploy options may resolve persistent failures.

Q: Is it possible to upgrade an already deployed NFT contract?A: Standard ERC-721 contracts are immutable once deployed. Proxy patterns like Transparent Proxy or UUPS require architectural changes before deployment.

Q: How do I handle metadata storage when deploying to Ethereum mainnet?A: Storing URIs off-chain is standard practice. You can host JSON files on IPFS, Filecoin, or decentralized CDNs and reference their CIDs in tokenURI.