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Verify smart contracts with Hardhat

This page outlines the steps for verifying contracts on Neon EVM using the Hardhat tool.

Before beginning the tutorial below, make sure that you have properly configured Hardhat for Neon EVM.

This tutorial is based on the example located in this repository.

By the end of this tutorial, you will learn to verify a contract that deploys an ERC-20 token to Neon EVM Devnet on Neonscan and Blockscout explorers.

Step 1: Deploy the contract​

To deploy a contract, please follow this page describing how to deploy contracts with Hardhat.

Step 2: Verify the deployed contract​

To verify the deployed contract from the above step, let's take an example of a deployed contract with address 0xf4f09428C61c5F91c6F6B9a1A422778F0473eA08 on Neon EVM Devnet.

  1. Add these lines to hardhat.config.js -
etherscan: {
    apiKey: {
      neonevm: "test",
    },
    customChains: [
      {
        network: "neonevm",
        chainId: 245022926,
        urls: {
          apiURL: "https://devnet-api.neonscan.org/hardhat/verify",
          browserURL: "https://devnet.neonscan.org",
        },
      },
      {
        network: "neonevm",
        chainId: 245022934,
        urls: {
          apiURL: "https://api.neonscan.org/hardhat/verify",
          browserURL: "https://neonscan.org",
        },
      },
    ],
},
  1. After running the following command to verify -
npx hardhat verify --network neondevnet 0xf4f09428C61c5F91c6F6B9a1A422778F0473eA08

The output should look like this -

Successfully submitted source code for contract
contracts/TestERC20/TestERC20.sol:TestERC20Hardhat at 0xf4f09428C61c5F91c6F6B9a1A422778F0473eA08
for verification on the block explorer. Waiting for verification result...

Successfully verified contract TestERC20Hardhat on the block explorer.
https://devnet.neonscan.org/address/0xf4f09428C61c5F91c6F6B9a1A422778F0473eA08#code

The verified contract source code can be found here https://devnet.neonscan.org/address/0xf4f09428C61c5F91c6F6B9a1A422778F0473eA08#contract.

important

If the deployed contract consists of constructor arguments to be passed, then the command for verification should be -

npx hardhat verify --network neondevnet <CONTRACT_ADDRESS> <ARGUMENT_1> <ARGUMENT_2>
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