Similar to the hardhat verification plugin,this plugin submits the contract source and other info of all deployed contracts to Sourcify.

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Verify

Similar to the verification approach described in the hardhat verification plugin, you can verify the contract source code in the Sourcify as well by setting the following in the hardhat config file: 
// ...
const config: HardhatUserConfig = {
  // ...
  sourcify: {
    enabled: true
  },
  // ...
};

export default config;

npx hardhat verify --network <network> DEPLOYED_CONTRACT_ADDRESS "Constructor argument 1"
Optimism Sepolia example: 
> npx hardhat verify --network optimism-sepolia 0xCD562a6426b474390A9E7e554b9B4f9f62Ea38Ba 1234
Successfully submitted source code for contract
contracts/Lock.sol:Lock at 0xCD562a6426b474390A9E7e554b9B4f9f62Ea38Ba
for verification on the block explorer. Waiting for verification result...

Successfully verified contract Lock on the block explorer.
https://optimism-sepolia.blockscout.com/address/0xCD562a6426b474390A9E7e554b9B4f9f62Ea38Ba#code

Successfully verified contract Lock on Sourcify.
https://repo.sourcify.dev/contracts/full_match/11155420/0xCD562a6426b474390A9E7e554b9B4f9f62Ea38Ba/

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Confirm Verification on BlockScout

Go to your BlockScout instance and paste the contract address into the search bar.
Scroll down to see verified status. A green checkmark ✅ means the contract is verified.
If your screen size is limited, you may need to click the 3 dots to view and click through to the contract.
Scroll down to see and interact with the contract code.