Verify Smart Contract with Hardhat

Code of honor: This tutorial is based on the post from https://openzeppelin.com/ Thanks for your contributions!

Hardhat has an Etherscan plugin: Hardhat Bscscan plugin

Please read this blog to lean about the fundamentals of Hardhat.

Install the plugin

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

Go to BSCScan and register an API key: https://bscscan.com/myapikey

Configure the plugin in buidler.config.js

• Add require("@nomiclabs/hardhat-etherscan");
• Add Bscscan API key

Warning
keep secret and don’t commit to version control

• Set compiler version to match what was deployed

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

require('@nomiclabs/hardhat-ethers');
require("@nomiclabs/hardhat-etherscan");
/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {

  networks: {
    testnet: {
      url: `https://data-seed-prebsc-1-s1.binance.org:8545`,
      accounts: {mnemonic: mnemonic}
    },
    mainnet: {
      url: `https://bsc-dataseed.binance.org/`,
      accounts: {mnemonic: mnemonic}
    }
  },

  etherscan: {
    // Your API key for Etherscan
    // Obtain one at https://bscscan.com/
    apiKey: bscscanApiKey
  },
  solidity: "0.5.12"
};

Verify

Warning
Remove any unnecessary contracts and clear the artifacts otherwise these will also be part of the verified contract.

Run the following command:

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

• Example on testnet

$ npx hardhat  verify --network testnet 0xbF39886B4F91F5170934191b0d96Dd277147FBB2
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 on Etherscan.
https://testnet.bscscan.com/address/0xbF39886B4F91F5170934191b0d96Dd277147FBB2#code