Hardhat

Learn how to verify smart contracts on the Filecoin network using Hardhat with various verification services including Blockscout, Sourcify, and Filfox.

This guide shows you how to verify your smart contracts using Hardhat on the Filecoin network.

Prerequisites

• A Hardhat project set up for Filecoin development

• If you don't have a Hardhat project, check out the FEVM Hardhat Kit

• A deployed contract address

• Contract constructor arguments (if any)

Verification Methods

Blockscout Verification

Blockscout is a popular blockchain explorer that supports contract verification. Add the following configuration to your hardhat.config.ts:

const config: HardhatUserConfig = {
  solidity: {
    ...
  },
  networks: {
    filecoin: {
      ...
    },
    calibration: {
      ...
    },
  },
  // Configuration for hardhat-verify plugin with Blockscout API
  etherscan: {
    apiKey: {
      filecoin: "empty",
      calibration: "empty",
    },
    customChains: [
      {
        network: "filecoin",
        chainId: 314,
        urls: {
          apiURL: "https://filecoin.blockscout.com/api",
          browserURL: "https://filecoin.blockscout.com",
        },
      },
      {
        network: "calibration",
        chainId: 314159,
        urls: {
          apiURL: "https://filecoin-testnet.blockscout.com/api",
          browserURL: "https://filecoin-testnet.blockscout.com",
        },
      },
    ],
  }
};

export default config;

Verify on Filecoin Mainnet:

npx hardhat verify $CONTRACT_ADDRESS_TO_VERIFY $CONTRACT_CONSTRUCTOR_ARGS --network filecoin

Verify on Calibration Testnet:

npx hardhat verify $CONTRACT_ADDRESS_TO_VERIFY $CONTRACT_CONSTRUCTOR_ARGS --network calibration

Troubleshooting: If your contract appears already verified but shows a mismatch, use the --force flag:

npx hardhat verify $CONTRACT_ADDRESS_TO_VERIFY $CONTRACT_CONSTRUCTOR_ARGS --network filecoin --force

Sourcify Verification

Sourcify provides decentralized contract verification. Include the Blockscout configuration above and add the following Sourcify configuration:

const config: HardhatUserConfig = {
  ...
  // Configuration for hardhat-verify plugin to also verify on Sourcify
  sourcify: {
    enabled: true, // verifies both on Sourcify and on Blockscout
    // Optional: specify a different Sourcify server
    apiUrl: "https://sourcify.dev/server",
    // Optional: specify a different Sourcify repository
    browserUrl: "https://repo.sourcify.dev",
  },
};

export default config;

This configuration enables dual verification on both Sourcify and Blockscout when running the npx hardhat verify task.

For more information, see the Sourcify documentation.

Filfox Verification

Filfox is the native Filecoin explorer with dedicated verification support.

Installation:

Install the @fil-b/filfox-verifier package into your Hardhat project.

npm install -g @fil-b/filfox-verifier

Configuration: Import the plugin in your Hardhat configuration file. This will add the verifyfilfox task into your Hardhat project!

// hardhat.config.js
require("@fil-b/filfox-verifier/hardhat");

// or in hardhat.config.ts
import "@fil-b/filfox-verifier/hardhat";

Usage:

# Verify on Filecoin Mainnet
npx hardhat verifyfilfox --address 0xYourContractAddress --network filecoin

# Verify on Calibration Testnet
npx hardhat verifyfilfox --address 0xYourContractAddress --network calibration

For detailed information, see the @fil-b/filfox-verifier documentation.

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