Official BASE documentation related
This section will guide you through deploying an NFT smart contract (ERC-721) to the Base network using Hardhat.
Hardhat is a developer tool that provides a simple way to deploy, test, and debug smart contracts.
The project is uses dotenv to load the WALLET_KEY environment variable from a .env file to process.env.WALLET_KEY. You should use a similar method to avoid hardcoding your private keys within your source code. And is used Blockscout API key you should add the BLOCKSCOUT_KEY environment variable to your .env file.