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Getting Started with MetaMask

Introduction

MetaMask is a convenient UI for interacting with Ethereum-compatible blockchains (such as Aurora). For the purpose of this guide, we will assume you are already familiar with MetaMask and have it installed. If you need help getting started with MetaMask itself, check out their documentation.

In this tutorial we will walk through connecting MetaMask to the Aurora Testnet, deploying a simple ERC-20 contract using Remix, and transferring the new token using MetaMask.

Note

Screenshots in this tutorial are taken from the MetaMask browser extension version 9.5.5.

Connecting MetaMask to Aurora

In the top-right corner of the MetaMask interface, click the network selection drop-down and then click Custom RPC.

MetaMask-network-select

Fill in the form with the following information:

  • Network Name: Aurora Testnet
  • New RPC URL: https://testnet.aurora.dev/
  • Chain ID: 1313161555
  • Currency Symbol: ETH

MetaMask-create-aurora-rpc

Note

All the Aurora RPC endpoint URLs and chain IDs can be found on our Networks page.

Click Save, and you should see Aurora Testnet is now the network selected in MetaMask. To see MetaMask in action, we will connect it to Remix and perform some transactions.

Deploying an ERC-20 Token using Remix

In a new tab, open the Remix IDE at remix.ethereum.org. It might take a minute to load, but once it has, create a new file ERC20Token.sol in the workspace panel on the left:

Remix-new-file

Copy and paste the following code into the central editor panel:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.0.0/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20 {
    constructor (string memory name, string memory symbol) ERC20(name, symbol) {
        // Mint 100 tokens to msg.sender
        // Similar to how
        // 1 dollar = 100 cents
        // 1 token = 1 * (10 ** decimals)
        _mint(msg.sender, 100 * 10 ** uint(decimals()));
    }
}

This code is a slightly modified (the Solidity compiler and OpenZeppelin versions are newer) version of the example from Solidity by Example.

Click the Solidity Compile button on the far left panel (the second icon down); ensure your selected Solidity compiler version is 0.8 (minor versions within 0.8, e.g., 0.8.4 work too), and click Compile ERC20Token.sol.

Remix-solidity-compile

Once the contract is compiled, click the Deploy & run transactions button in the far left panel (the icon below the Solidity compiler). In the ENVIRONMENT drop-down select Injected Web3.

Remix-inject-web3

You will see a MetaMask pop-up window asking you to give the Remix IDE permission to access it. Click Next and then Connect to grant access.

Remix-connect-metamask

Back in the Remix interface, click the arrow next to the DEPLOY section of the left panel. Fill in the token details with whatever you like (MyToken and MT in the example), and click transact.

Remix-deploy-contract

Another MetaMask pop-up will appear asking you to confirm the transaction. Click Confirm.

Remix-deploy-contract-metamask-confirm

Note

You may be surprised to see the gas price set to zero in this transaction. During the early access period Aurora transactions are free, however this will change in the future. Not to worry, even when transaction fees will be non-zero, they'll still be much lower than on the Ethereum 1.0 Mainnet.

After a few moments the transaction will be confirmed by the network. You will see a success message in the bottom panel and the contract listed under Deployed Contracts on the left panel. Click the copy button to copy the address of the newly deployed contract.

Remix-deploy-contract-confirmed

Now that the contract is deployed on the Aurora network, we can interact with it via MetaMask.

Adding an ERC-20 Token to MetaMask

In the MetaMask interface (with the Aurora Testnet network still selected), click the Add Token button:

MetaMask-add-token-button

Paste the token address copied from Remix in the previous step. The remaining token details should fill in automatically as MetaMask finds the contract on-chain. Click Next:

MetaMask-add-token

On the next screen you see the balance (100 tokens), as minted in our contract constructor. Click Add Tokens:

MetaMask-add-token-confirm

The token has now been added to MetaMask and we can use the MetaMask interface to view the token balance and to transfer the token to others.

Transferring an ERC-20 Token with MetaMask

Continuing from the previous step, click the Send button in the MetaMask interface:

MetaMask-my-token

Select a recipient (if you have multiple accounts in MetaMask you can simply select another account), and an amount of tokens to send. Click Next:

MetaMask-send-my-token

Note

Once again the gas price should be set to zero, but this will change going forward.

Click Confirm to send the transaction to the network:

MetaMask-send-my-token-confirm

After a few moments the transaction will be confirmed by the network. You can see the updated balance your account holds in the MetaMask interface:

MetaMask-my-token-sent-account1

If you transferred to another MetaMask account you hold then you can follow the aforementioned instructions for adding the token to MetaMask on the other account, and view its balance also.

MetaMask-add-token-account2

Summary

In this tutorial we connected MetaMask to the Aurora Testnet, deployed an ERC-20 token contract using Remix, and transferred that token using MetaMask. The only difference to doing this on the original Ethereum network was setting the RPC endpoint to be Aurora's.