> For the complete documentation index, see [llms.txt](/llms.txt).

# Run a development network

Run a personal Ethereum development network using [Hardhat](https://hardhat.org/hardhat-network/docs/overview#hardhat-network)to develop a dapp in a secure test environment.

note

When using a local development blockchain such as Hardhat Network or [anvil](https://book.getfoundry.sh/anvil/#overview-of-anvil), your node must calculate gas to make transactions on MetaMask.

## Connect to Hardhat[​](#connect-to-hardhat "Direct link to Connect to Hardhat")

Follow these steps to connect MetaMask to Hardhat Network.

1. [Set up a Hardhat project.](https://hardhat.org/hardhat-runner/docs/guides/project-setup)
2. Create a new [MetaMask seed phrase](https://support.metamask.io/privacy-and-security/what-is-a-secret-recovery-phrase-and-how-to-keep-your-crypto-wallet-secure/)specifically for development.  
important  
Your seed phrase controls all your accounts, so we recommend keeping at least one seed phrase for development, separate from any used to store real value. You can manage multiple seed phrases by using multiple browser profiles, each with its own MetaMask installation.
3. In your `hardhat.config.js` file, specify a [networks configuration](https://hardhat.org/hardhat-runner/docs/config#networks-configuration)with a `hardhat` network. In this `networks.hardhat` configuration:

  - Specify your MetaMask seed phrase in the [accounts.mnemonic](https://hardhat.org/hardhat-network/docs/reference#accounts) field.  
  tip  
  Alternatively, to prevent committing your seed phrase, we recommend adding your seed phrase to a [.env file](/services/how-to/javascript-dotenv/) and using the `process.env` global variable in `hardhat.config.js`.
  - Specify the [chain ID 1337](https://hardhat.org/hardhat-network/docs/metamask-issue) in the [chainId](https://hardhat.org/hardhat-network/docs/reference#chainid) field.  
For example:  
hardhat.config.js  
```  
module.exports = {  
  networks: {  
    hardhat: {  
      accounts: {  
        mnemonic: process.env.SEED_PHRASE,  
      },  
      chainId: 1337,  
    },  
  },  
}  
```  
Hardhat automatically gives each of your first 20 accounts 10000 test ether (you can modify these numbers in the [accounts](https://hardhat.org/hardhat-network/docs/reference#accounts)configuration), to quickly start development.
4. Run `npx hardhat node` to run Hardhat Network and expose a JSON-RPC interface.
5. Connect MetaMask to your Hardhat Network RPC URL, `http://127.0.0.1:8545/`. In the MetaMask extension:

  1. In the upper left corner, select the network you're currently connected to.
  2. Select **Add network**.
  3. Select **Add a network manually**.
  4. Enter your Hardhat Network RPC URL, `http://127.0.0.1:8545/` (or `http://localhost:8545`).
  5. Enter your Hardhat Network chain ID, `1337` (or `0x539` in hexadecimal format).  
tip  
Alternatively, you can add Hardhat Network to MetaMask using [wallet_addEthereumChain](/metamask-connect/evm/reference/json-rpc-api/).

## Reset your local nonce calculation[​](#reset-your-local-nonce-calculation "Direct link to Reset your local nonce calculation")

If you restart your development network, you can accidentally confuse MetaMask because it calculates the next nonce based on both the network state _and_ the known sent transactions.

To clear MetaMask's transaction queue and reset its nonce calculation, go to **Settings > Advanced**and select **Reset account**.

## Next steps[​](#next-steps "Direct link to Next steps")

- [Manage networks](/metamask-connect/evm/guides/manage-networks/)
- [Send transactions](/metamask-connect/evm/guides/send-transactions/)
- [Production readiness checklist](/metamask-connect/evm/guides/best-practices/production-readiness/)