Skip to content
Hardhat 3

Verifying a contract

When you deployed the Counter contract to the Sepolia network, Etherscan only showed you the raw bytecode of the contract. To see its source code, you need to verify it.

Getting an Etherscan API key

Section titled “Getting an Etherscan API key”

Before you can verify the contract, add an Etherscan API key to your configuration. If you don’t have one, learn how to obtain it here.

You need to add the API key to your config using a Configuration Variable:

hardhat.config.ts
import hardhatToolboxViemPlugin from "@nomicfoundation/hardhat-toolbox-viem";
import { configVariable, defineConfig } from "hardhat/config";


export default defineConfig({
  plugins: [hardhatToolboxViemPlugin],
  solidity: {
    version: "0.8.28",
  },
  networks: {
    sepolia: {
      type: "http",
      chainType: "l1",
      url: configVariable("SEPOLIA_RPC_URL"),
      accounts: [configVariable("SEPOLIA_PRIVATE_KEY")],
    },
  },
  verify: {
    etherscan: {
      apiKey: configVariable("ETHERSCAN_API_KEY"),
    },
  },
});

As you did before, add the ETHERSCAN_API_KEY variable to your keystore:

Terminal window
npx hardhat keystore set ETHERSCAN_API_KEY

Verifying your contract with Hardhat Ignition

Section titled “Verifying your contract with Hardhat Ignition”

Execute the Ignition module again with the --verify flag. Since you’ve already deployed the contracts, this won’t re-deploy them, but it will submit the source code to Etherscan for verification:

Terminal window
npx hardhat ignition deploy ignition/modules/Counter.ts --network sepolia --verify

If everything goes well, you’ll see output indicating successful verification and a link to the verified contract on Sepolia Etherscan.