📝 Building Your First Smart Contract on Arbitrum (Without Losing Your Mind)

#ethereum #web3 #smartcontract #etherjs

So you’ve heard the buzz about Arbitrum…
Low gas fees?
Fast transactions?
Ethereum compatibility?
Now you’re ready to build.

Let’s walk you through your first smart contract on Arbitrum — step by step.

🚧 What We’re Building

We’ll build a simple “On-chain Guestbook”.
Users can submit their name and a message.
The data is stored publicly on the blockchain.
It’s like Web3 Twitter, but way cooler.

🛠 Tools We’ll Use

Solidity – Smart contract language
Hardhat – Framework for writing solidity
MetaMask – Your wallet for signing transactions
Arbitrum Sepolia Testnet – So you can deploy for free
TailwindCSS + JS – For the frontend (covered in next post)

⚙️ Step 1: Set Up MetaMask for Arbitrum Sepolia

1. Open MetaMask

2. Select the network dropdown

3. Scroll down and activate testnets, choose sepolia

Fund your testnet Go to Google Cloud Web3 to fund your account

✍️ Step 2: Write the Guestbook Smart Contract

1. Open Hardhat and install the hardhat package(Hardhat is a framework that helps you write smart contract)

2. Smart Contract

3. Getting your RPC and Private Key
Go to Infura to get your RPC link(this is a gateway for web3 application to connect to the blockchain node).

You need your Private Key:

Open your Metamask

Select the dropdown icon on your right

Select Account Details

Click on Show Private Key

It will request for your password

You click on the button to reveal your private key

4. Config your Hardhat Config
You need to install dotenv, to hard your private key and RPC API Key

 npm install dotenv

5. Write your deployment Code

6. Deployed to TestNet

💡 What You’ve Learned

✅ How to configure MetaMask for Arbitrum
✅ How to write and deploy a Solidity contract
✅ How to store and read data on-chain
✅ How easy it is to build on Arbitrum

Get the code from my github account