Verify Smart Contract with Hardhat

Install the plugin

To begin the smart contract verification process using Hardhat, you need to install the Hardhat Etherscan plugin. This plugin enables seamless integration between your Hardhat development environment and blockchain explorers like BSCScan, allowing you to verify your deployed smart contracts on the blockchain.

Install the plugin by running the following command in your project directory:

npm install --save-dev @nomiclabs/hardhat-etherscan

After installation, navigate to the appropriate blockchain explorer for your network and register an API key. This API key is essential for authenticating your verification requests and will be used in the configuration step.

Configure the plugin in hardhat.config.js

Once the plugin is installed, you need to configure it in your hardhat.config.js file. This configuration ensures that Hardhat knows how to communicate with the blockchain explorer and has all necessary credentials to verify your contracts.

Add the following configurations to your hardhat.config.js:

1. Import the Hardhat Etherscan plugin using require("@nomiclabs/hardhat-etherscan")
2. Add your blockchain explorer API key to the configuration
3. Set the Solidity compiler version to match the version used when deploying your contract

Here is a sample configuration file:

// hardhat.config.js
const { mnemonic, explorerApiKey } = require('./secrets.json');

require('@nomiclabs/hardhat-[etherscan](https://dex.gate.com/crypto-wiki/article/how-to-use-etherscan-to-navigate-the-blockchain-20251127)');

/**
 * @type {import('hardhat/config').HardhatUserConfig}
 */
module.exports = {
  networks: {
    testnet: {
      url: `https://data-seed-prebsc-1-e05a8b61d2d5ddd83ebdd5dc0ee2d25c6330ee4393a2d6a27465d41bc47f274a.bnbchain.org:2053`,
      accounts: { mnemonic: mnemonic }
    },
    mainnet: {
      url: `https://bsc-dataseed1.bnbchain.org:443`,
      accounts: { mnemonic: mnemonic }
    }
  },
  etherscan: {
    apiKey: explorerApiKey
  },
  solidity: "0.5.12"
};

Ensure that your network configurations point to the correct RPC endpoints and that your Solidity compiler version matches your smart contract.

Verify

With the plugin installed and configured, you can now verify your smart contract on the blockchain explorer. Before running the verification command, it is recommended to remove any unnecessary contracts from your project and clear the artifacts directory. This prevents unrelated contracts from being included in the verification process.

Run the verification command with the following syntax:

npx hardhat verify --network mainnet DEPLOYED_CONTRACT_ADDRESS "Constructor argument 1"

For example, if you are verifying a contract on the testnet, the command would look like this:

npx hardhat verify --network testnet 0xbF39886B4F91F5170934191b0d96Dd277147FBB2

Upon successful execution, you will see output confirming the verification:

Nothing to compile
Compiling 1 file with 0.5.16
Successfully submitted source code for contract
contracts/BEP20Token.sol:BEP20Token at 0xbF39886B4F91F5170934191b0d96Dd277147FBB2
for verification on Etherscan. Waiting for verification result...

Successfully verified contract [BEP20Token](https://dex.gate.com/crypto-wiki/article/849b8dd7-2cc3-4d63-90ea-8438c4ed8a17) on Etherscan.

This output indicates that your smart contract has been successfully verified and is now publicly viewable on the blockchain explorer.

Conclusion

Verifying smart contracts with Hardhat verify functionality and blockchain explorers is a straightforward process that enhances transparency and security in the blockchain ecosystem. By installing the Hardhat Etherscan plugin, properly configuring your hardhat.config.js file with the correct API key and network settings, and executing the verification command, you can ensure that your deployed smart contracts are verified and auditable on the blockchain. This process builds trust with users and stakeholders by making your contract source code publicly available for review and validation.

FAQ

What is hardhat used for?

Hardhat is a development environment for Ethereum smart contracts. It enables developers to compile, deploy, test, and debug code efficiently on local networks and testnets.

How to verify a smart contract?

Use verification tools to confirm the bytecode matches your source code. Submit your contract source code, compiler version, and constructor parameters to the verification service. Once verified, the contract source becomes publicly viewable and trusted.

How to check if a smart contract is legit?

Verify the contract address on a block explorer, review its recent transaction history, check if the associated token is legitimate, and ensure the contract's functions align with its stated purpose.