Welcome to the NZRT Wiki Podcast. Today we’re looking at Etherscan & Basescan.

If you’ve ever deployed a smart contract and wondered how anyone is supposed to trust it, this is the tool that answers that question. Basescan is the block explorer for the Base network, and it’s one of the most important things you’ll use when working with blockchain development at NZRT. It lets you verify contracts, inspect transactions, and expose your contract’s ABI publicly so that other developers and users can see exactly what your contract does. The same family of tools includes Etherscan, which covers the Ethereum mainnet. Think of these explorers as a public ledger viewer — a window into everything that’s happening on the chain.

Let’s start with the three explorers you need to know about. For the Base mainnet, you head to basescan dot org. For Base Sepolia, which is the test network you’ll use during development, you go to sepolia dot basescan dot org. And for the Ethereum mainnet, the address is etherscan dot io. Those are your three primary URLs, and which one you use depends entirely on which network you’re working on.

Now let’s talk about contract verification, because this is probably the most important thing you’ll do with Basescan. When you verify a contract, you’re publishing its source code publicly on Basescan. This matters for two big reasons. First, it means the public ABI — that’s the application binary interface, essentially the list of functions your contract exposes — becomes accessible to anyone. Second, it makes transactions human-readable. Instead of seeing a wall of encoded hex data, people can actually see what a transaction is doing in plain terms.

To verify a contract, you use Hardhat from your terminal. The first code example shows the general command structure. You run Hardhat’s verify task, specify which network you’re targeting — in this case Base Sepolia — then provide the contract’s deployed address, followed by any constructor arguments your contract was deployed with. So if your contract took two arguments when it was first deployed, you pass both of those in order after the address.

The second example makes this concrete. It shows verifying the ITSL Token contract on Base Sepolia, where the contract was deployed with an initial supply of one million tokens. So the command passes the contract address and then that initial supply value as the constructor argument.

One thing to keep in mind before any of this works: you need a Basescan API key, and it needs to be stored in your dot env file under the name BASESCAN underscore API underscore KEY. At NZRT, you’ll find the API key stored under ITE slash Blockchain slash Etherscan in the credentials system — so check there first before going looking elsewhere.

Once your contract is verified, Basescan becomes a really powerful inspection tool. There are six key things you can check, and knowing where to find each one will save you a lot of time. First, to confirm a contract is actually verified, you go to the Contract tab and look for a green checkmark — that’s your confirmation. Second, if you want to read data from the contract, you go to Contract and then Read Contract — this shows you all the view functions and lets you call them directly from the browser without spending any gas. Third, if you need to interact with state-changing functions, you go to Contract and then Write Contract — this is where you can call functions that modify the blockchain state, and you’ll need a connected wallet to do it. Fourth, to see who holds tokens associated with the contract, you go to Token and then Holders. Fifth, for a full history of every transaction that’s touched the contract, you check the Transactions tab. And sixth, if you want to see event logs — things the contract has emitted during its lifetime — you go to the Events tab.

Those six checks cover the vast majority of what you’ll need day to day when monitoring or debugging a deployed contract. Whether you’re confirming a deployment went through, checking that a function returned the right value, or auditing token distribution, Basescan puts all of that in one place.

If you want to dig deeper into the workflow around deploying and verifying contracts, the related topics to look up in the wiki are Hardhat and Contract Verification — those will give you the full picture of the development and deployment pipeline that feeds into what you’ve heard today.

That’s it for this episode of the NZRT Wiki Podcast. Thanks for listening.