Skip to main content
Make sure you’ve updated to @nomicfoundation/hardhat-verify@^2.0.14, see migrating notes if you have an existing project.
Hardhat is a smart contracts development tool, perfect if you’re familiar with Javascript/Typescript. If you’ve yet to setup Hardhat, here’s the official guide, the following steps are to setup the verification plugin.

​
Install

Via npm. 
npm i @nomicfoundation/hardhat-verify

​
Config

In hardhat.config.ts, import the plugin. 
import "@nomicfoundation/hardhat-verify";
Add your Etherscan key. 
config: HardhatUserConfig = {
  solidity: "0.8.28",
  networks: {
    sepolia: {
      url: `https://1rpc.io/sepolia`,
      accounts: [SEPOLIA_PRIVATE_KEY],
    },
  },
   etherscan: {
    apiKey: "YourEtherscanApiKey"
  }
};

​
Deploy and Verify

npx hardhat ignition deploy ./ignition/modules/Lock.ts --network sepolia --verify

​
Verify an Existing Contract

npx hardhat verify --network sepolia 0xdCBdBAA8404554502B433106e62728B659aCfE3b

​
Custom Chains

For super new Etherscan based explorers that are not supported by Hardhat yet, you can add them as a customChain in hardhat.config.ts. 
etherscan: {
    apiKey: "YourEtherscanApiKey",
    customChains: [
    {
      network: "sonic",
      chainId: 146,
      urls: {
        apiURL: "https://api.etherscan.io/v2/api",
        browserURL: "https://sonicscan.org"
      }
    },
    {
      network: "katana",
      chainId: 146,
      urls: {
        apiURL: "https://api.etherscan.io/v2/api",
        browserURL: "https://sonicscan.org"
      }
    }
  ]
}

​
Migrating from V1

API keys from any other explorer (such as BscScan/Basescan/Arbiscan) have been deprecated.
This change largely affects the hardhat.config.ts file — good riddance to the long customChains entries for each explorer. Update your config to a single Etherscan apiKey entry as per above.
This open source integration was shipped by @antico5 and the Hardhat team.