Getting Started with MetaMask

Open the Google Chrome browser and navigate to https://chrome.google.com/webstore/category/extensions.

Search for “MetaMask” and click on the logo of a fox. You should see something like the result shown in The detail page of the MetaMask Chrome extension.

Figure 1. The detail page of the MetaMask Chrome extension

It’s important to verify that you are downloading the real MetaMask extension, as sometimes people are able to sneak malicious extensions past Google’s filters. The real one:

• Shows the ID nkbihfbeogaeaoehlefnkodbefgpgknn in the address bar

• Is offered by https://metamask.io

• Has more than 1,500 reviews

• Has more than 1,000,000 users

Once you confirm you are looking at the correct extension, click “Add to Chrome” to install it.

Creating a Wallet

Once MetaMask is installed you should see a new icon (the head of a fox) in your browser’s toolbar. Click on it to get started. You will be asked to accept the terms and conditions and then to create your new Ethereum wallet by entering a password (see The password page of the MetaMask Chrome extension).

Figure 2. The password page of the MetaMask Chrome extension

Once you’ve set a password, MetaMask will generate a wallet for you and show you a mnemonic backup consisting of 12 English words (see The mnemonic backup of your wallet, created by MetaMask). These words can be used in any compatible wallet to recover access to your funds should something happen to MetaMask or your computer. You do not need the password for this recovery; the 12 words are sufficient.

Figure 3. The mnemonic backup of your wallet, created by MetaMask

Once you have confirmed that you have stored the mnemonic securely, you’ll be able to see the details of your Ethereum account, as shown in Your Ethereum account in MetaMask.

Figure 4. Your Ethereum account in MetaMask

Your account page shows the name of your account (“Account 1” by default), an Ethereum address (0x9E713… in the example), and a colorful icon to help you visually distinguish this account from other accounts. At the top of the account page, you can see which Ethereum network you are currently working on (“Main Network” in the example).

Congratulations! You have set up your first Ethereum wallet.

Switching Networks

As you can see on the MetaMask account page, you can choose between multiple Ethereum networks. By default, MetaMask will try to connect to the main network. The other choices are public testnets, any Ethereum node of your choice, or nodes running private blockchains on your own computer (localhost):

Main Ethereum Network

The main public Ethereum blockchain. Real ETH, real value, and real consequences.

Ropsten Test Network

Ethereum public test blockchain and network. ETH on this network has no value.

Kovan Test Network

Ethereum public test blockchain and network using the Aura consensus protocol with proof of authority (federated signing). ETH on this network has no value. The Kovan test network is supported by Parity only. Other Ethereum clients use the Clique consensus protocol, which was proposed later, for proof of authority–based verification.

Rinkeby Test Network

Ethereum public test blockchain and network, using the Clique consensus protocol with proof of authority (federated signing). ETH on this network has no value.

Localhost 8545

Connects to a node running on the same computer as the browser. The node can be part of any public blockchain (main or testnet), or a private testnet.

Custom RPC

Allows you to connect MetaMask to any node with a Geth-compatible Remote Procedure Call (RPC) interface. The node can be part of any public or private blockchain.

Getting Some Test Ether

Your first task is to get your wallet funded. You won’t be doing that on the main network because real ether costs money and handling it requires a bit more experience. For now, you’ll load your wallet with some testnet ether.

Switch MetaMask to the Ropsten Test Network. Click Deposit, then click Ropsten Test Faucet. MetaMask will open a new web page, as shown in MetaMask Ropsten Test Faucet.

Figure 5. MetaMask Ropsten Test Faucet

You may notice that the web page already contains your MetaMask wallet’s Ethereum address. MetaMask integrates Ethereum-enabled web pages with your MetaMask wallet and can “see” Ethereum addresses on the web page, allowing you, for example, to send a payment to an online shop displaying an Ethereum address. MetaMask can also populate the web page with your own wallet’s address as a recipient address if the web page requests it. In this page, the faucet application is asking MetaMask for a wallet address to send test ether to.

Click the green “request 1 ether from faucet” button. You will see a transaction ID appear in the lower part of the page. The faucet app has created a transaction—a payment to you. The transaction ID looks like this:

0x7c7ad5aaea6474adccf6f5c5d6abed11b70a350fbc6f9590109e099568090c57

In a few seconds, the new transaction will be mined by the Ropsten miners and your MetaMask wallet will show a balance of 1 ETH. Click on the transaction ID and your browser will take you to a block explorer, which is a website that allows you to visualize and explore blocks, addresses, and transactions. MetaMask uses the Etherscan block explorer, one of the more popular Ethereum block explorers. The transaction containing the payment from the Ropsten Test Faucet is shown in Etherscan Ropsten block explorer.

Figure 6. Etherscan Ropsten block explorer

The transaction has been recorded on the Ropsten blockchain and can be viewed at any time by anyone, simply by searching for the transaction ID, or visiting the link.

Try visiting that link, or entering the transaction hash into the ropsten.etherscan.io website, to see it for yourself.

Sending Ether from MetaMask

Once you’ve received your first test ether from the Ropsten Test Faucet, you can experiment with sending ether by trying to send some back to the faucet. As you can see on the Ropsten Test Faucet page, there is an option to “donate” 1 ETH to the faucet. This option is available so that once you’re done testing, you can return the remainder of your test ether, so that someone else can use it next. Even though test ether has no value, some people hoard it, making it difficult for everyone else to use the test networks. Hoarding test ether is frowned upon!

Fortunately, we are not test ether hoarders. Click the orange “1 ether” button to tell MetaMask to create a transaction paying the faucet 1 ether. MetaMask will prepare a transaction and pop up a window with the confirmation, as shown in Sending 1 ether to the faucet.

Figure 7. Sending 1 ether to the faucet

Oops! You probably noticed you can’t complete the transaction—MetaMask says you have an insufficient balance. At first glance this may seem confusing: you have 1 ETH, you want to send 1 ETH, so why is MetaMask saying you have insufficient funds?

The answer is because of the cost of gas. Every Ethereum transaction requires payment of a fee, which is collected by the miners to validate the transaction. The fees in Ethereum are charged in a virtual currency called gas. You pay for the gas with ether, as part of the transaction.

When you sent the transaction, MetaMask calculated the average gas price of recent successful transactions at 3 gwei, which stands for gigawei. Wei is the smallest subdivision of the ether currency, as we discussed in Ether Currency Units. The gas limit is set at the cost of sending a basic transaction, which is 21,000 gas units. Therefore, the maximum amount of ETH you will spend is 3 * 21,000 gwei = 63,000 gwei = 0.000063 ETH. (Be advised that average gas prices can fluctuate, as they are predominantly determined by miners. We will see in a later chapter how you can increase/decrease your gas limit to ensure your transaction takes precedence if need be.)

All this to say: making a 1 ETH transaction costs 1.000063 ETH. MetaMask confusingly rounds that down to 1 ETH when showing the total, but the actual amount you need is 1.000063 ETH and you only have 1 ETH. Click Reject to cancel this transaction.

Let’s get some more test ether! Click the green “request 1 ether from the faucet” button again and wait a few seconds. Don’t worry, the faucet should have plenty of ether and will give you more if you ask.

Once you have a balance of 2 ETH, you can try again. This time, when you click the orange “1 ether” donation button, you have sufficient balance to complete the transaction. Click Submit when MetaMask pops up the payment window. After all of this, you should see a balance of 0.999937 ETH because you sent 1 ETH to the faucet with 0.000063 ETH in gas.

Exploring the Transaction History of an Address

By now you have become an expert in using MetaMask to send and receive test ether. Your wallet has received at least two payments and sent at least one. You can view all these transactions using the ropsten.etherscan.io block explorer. You can either copy your wallet address and paste it into the block explorer’s search box, or have MetaMask open the page for you. Next to your account icon in MetaMask, you will see a button showing three dots. Click on it to show a menu of account-related options (see MetaMask account context menu).

Figure 8. MetaMask account context menu

Select “View account on Etherscan” to open a web page in the block explorer showing your account’s transaction history, as shown in Address transaction history on Etherscan.

Figure 9. Address transaction history on Etherscan

Here you can see the entire transaction history of your Ethereum address. It shows all the transactions recorded on the Ropsten blockchain where your address is the sender or recipient. Click on a few of these transactions to see more details.

You can explore the transaction history of any address. Take a look at the transaction history of the Ropsten Test Faucet address (hint: it is the “sender” address listed in the oldest payment to your address). You can see all the test ether sent from the faucet to you and to other addresses. Every transaction you see can lead you to more addresses and more transactions. Before long you will be lost in the maze of interconnected data. Public blockchains contain an enormous wealth of information, all of which can be explored programmatically, as we will see in future examples.