# Verifying a contract

Description: Hardhat 3 Tutorial - Verifying a contract on Etherscan

Note: This document was authored using MDX

  Source: https://github.com/NomicFoundation/hardhat-website/tree/main/src/content/docs/docs/tutorial/verifying.mdx

  Components used in this page:
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    - :::note: An informational callout block. Supports custom title `:::note[Title]` and icon `:::note{icon="name"}` syntax.
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import Run from "@hh/Run.astro";

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.

:::note
If you deploy a contract with a source that has already been verified on Etherscan, it will be automatically verified upon deployment. That's why you added a comment with a random number at the end of the `Counter.sol` file: to make the source code unique and avoid that automatic verification.
:::

## 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](https://etherscan.io/myapikey).

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

```ts ins={18-22}
// 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:

<Run command="hardhat keystore set ETHERSCAN_API_KEY" />

## 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:

<Run command="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.

:::tip
Learn more about contract verification in [our guide](/docs/guides/smart-contract-verification) and the [`hardhat-verify` plugin docs](/docs/plugins/hardhat-verify), which also supports Blockscout, Sourcify, and contracts that haven't been deployed with Hardhat Ignition.
:::