> ## Documentation Index
> Fetch the complete documentation index at: https://docs.monad.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Verify a smart contract on Monad using Hardhat

Once your contract is deployed to a live network, the next step is to verify its source code on the block explorer.

Verifying a contract means uploading its source code, along with the settings used to compile the code, to a
repository (typically maintained by a block explorer). This allows anyone to compile it and compare the generated
bytecode with what is deployed on chain. Doing this is extremely important in an open platform like Monad.

In this guide we'll explain how to do this using [Hardhat](https://hardhat.org/).

<Tip>
  The verification command may show an error message, but this is often misleading - the contract is usually verified successfully on both Sourcify and MonadScan. Check the explorer links to confirm verification.
</Tip>

<Tabs>
  <Tab title="Hardhat 2">
    ## Hardhat 2 Verification

    The `hardhat-monad` template is pre-configured to verify contracts on both MonadVision (Sourcify) and Monadscan (Etherscan) simultaneously.

    If you're using the template, your `hardhat.config.ts` should already have:

    ```ts theme={null}
    import type { HardhatUserConfig } from "hardhat/config";
    import "@nomicfoundation/hardhat-toolbox-viem";
    import "@nomicfoundation/hardhat-ignition-viem";
    import "dotenv/config";

    const PRIVATE_KEY = process.env.PRIVATE_KEY || "";
    const ETHERSCAN_API_KEY = process.env.ETHERSCAN_API_KEY || "";

    const config: HardhatUserConfig = {
      solidity: {
        version: "0.8.28",
        settings: {
          metadata: {
            bytecodeHash: "ipfs", // Required for Sourcify verification
          },
        },
      },
      networks: {
        monadTestnet: {
          url: "https://testnet-rpc.monad.xyz",
          accounts: [PRIVATE_KEY],
          chainId: 10143,
        },
        monadMainnet: {
          url: "https://rpc.monad.xyz",
          accounts: [PRIVATE_KEY],
          chainId: 143,
        },
      },
      sourcify: {
        enabled: true,
        apiUrl: "https://sourcify-api-monad.blockvision.org",
        browserUrl: "https://monadvision.com",
      },
      etherscan: {
        enabled: true,
        apiKey: {
          monadMainnet: ETHERSCAN_API_KEY,
          monadTestnet: ETHERSCAN_API_KEY,
        },
        customChains: [
          {
            network: "monadMainnet",
            chainId: 143,
            urls: {
              apiURL: "https://api.etherscan.io/v2/api?chainid=143",
              browserURL: "https://monadscan.com",
            },
          },
          {
            network: "monadTestnet",
            chainId: 10143,
            urls: {
              apiURL: "https://api.etherscan.io/v2/api?chainid=10143",
              browserURL: "https://testnet.monadscan.com",
            },
          },
        ],
      },
    };

    export default config;
    ```

    **Verify on Mainnet:**

    ```sh theme={null}
    npx hardhat verify <contract_address> --network monadMainnet
    ```

    **Verify on Testnet:**

    ```sh theme={null}
    npx hardhat verify <contract_address> --network monadTestnet
    ```

    This will verify your contract on both MonadVision and Monadscan. Once verified, you can view your contract on the respective explorers.
  </Tab>

  <Tab title="Hardhat 3">
    ## Hardhat 3 Verification

    <Tip>
      The verification command may show an error message, but this is often misleading - the contract is usually verified successfully on both Sourcify and MonadScan. Check the explorer links to confirm verification.
    </Tip>

    The `hardhat3-monad` template is pre-configured to verify contracts on both MonadVision (Sourcify) and Monadscan (Etherscan). Hardhat 3 uses a different configuration structure with the `verify` key and `chainDescriptors`.

    If you're using the template, your `hardhat.config.ts` should already have:

    ```ts theme={null}
    import hardhatToolboxViemPlugin from "@nomicfoundation/hardhat-toolbox-viem";
    import { defineConfig } from "hardhat/config";
    import "dotenv/config";

    const PRIVATE_KEY = process.env.PRIVATE_KEY || "";
    const ETHERSCAN_API_KEY = process.env.ETHERSCAN_API_KEY || "";

    export default defineConfig({
      plugins: [hardhatToolboxViemPlugin],
      solidity: {
        version: "0.8.28",
        settings: {
          optimizer: {
            enabled: true,
            runs: 200,
          },
        },
      },
      networks: {
        hardhat: {
          type: "edr-simulated",
        },
        monadTestnet: {
          type: "http",
          url: "https://testnet-rpc.monad.xyz",
          accounts: [PRIVATE_KEY],
          chainId: 10143,
        },
        monadMainnet: {
          type: "http",
          url: "https://rpc.monad.xyz",
          accounts: [PRIVATE_KEY],
          chainId: 143,
        },
      },
      verify: {
        blockscout: {
          enabled: false,
        },
        etherscan: {
          enabled: true,
          apiKey: ETHERSCAN_API_KEY,
        },
        sourcify: {
          enabled: true,
          apiUrl: "https://sourcify-api-monad.blockvision.org",
        },
      },
      chainDescriptors: {
        143: {
          name: "MonadMainnet",
          blockExplorers: {
            etherscan: {
              name: "Monadscan",
              url: "https://monadscan.com",
              apiUrl: "https://api.etherscan.io/v2/api",
            },
          },
        },
      },
    });
    ```

    **Verify on Mainnet:**

    ```sh theme={null}
    npx hardhat verify <contract_address> --network monadMainnet
    ```

    **Verify on Testnet:**

    ```sh theme={null}
    npx hardhat verify <contract_address> --network monadTestnet
    ```

    This will verify your contract on both MonadVision and Monadscan. Once verified, you can view your contract on the respective explorers.
  </Tab>
</Tabs>