# Quick Start zkLink Nova is EVM compatible. All the contracts and tools that work on Ethereum and L2s also work here, and you can easily fork and re-use functionality others have already built. This guide shows you how to deploy and interact with a smart contract on zkLink Nova Sepolia Testnet in less than 5 minutes. {% hint style="info" %} The execution layer of zkLink Nova is built on top of [ZK Stack](https://docs.zksync.io/zk-stack), which leverages the underlying technology of zkSync. **Building on zkLink Nova shares the same process of building on zkSync.** We recommend you to refer to the [documentation of zkSync](https://docs.zksync.io/build/) for more detailed information: {% endhint %} This is what we're going to do: * Fund your wallet with Sepolia Testnet ETH. * Use [zksync-cli](https://docs.zksync.io/build/tooling/zksync-cli/getting-started.html) to scaffold a new project. * Build a smart contract that stores a greeting message and deploy it to zkLink Nova testnet. * Run a script to retrieve and update the greeting message using [zksync-ethers](https://docs.zksync.io/build/sdks/js/getting-started.html). ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#prerequisites)Prerequisites * Make sure your machine satisfies the [system requirements](https://github.com/matter-labs/era-compiler-solidity/tree/main#system-requirements). * Download and install [Node.js](https://nodejs.org/en/download). * Use the `yarn` or `npm` package manager. We recommend using `yarn`. To install `yarn`, follow the [Yarn installation guide](https://yarnpkg.com/getting-started/install). * Learn how to [get your private key from your Metamask wallet](https://support.metamask.io/hc/en-us/articles/360015289632-How-to-export-an-account-s-private-key) as we'll use it to deploy a contract. ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#fund-your-wallet)Fund your wallet You can get Sepolia ETH from any of the following faucets and bridge it to zkLink Nova Testnet using the [zkLink Nova Bridge](https://sepolia.portal.zklink.io). * * * * You can check the balance of your account in the [zkLink Sepolia Explorer](https://sepolia.explorer.zklink.io). ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#create-the-project)Create the project {% hint style="info" %} **Project available in Atlas IDE** This entire tutorial can be run in under a minute using Atlas. Atlas is a smart contract IDE that lets you write, deploy, and interact with contracts from your browser. [Open this project in Atlas](https://app.atlaszk.com/projects?template=https://github.com/matter-labs/zksync-hardhat-template\&open=Greeter.sol\&chainId=300). {% endhint %} Run the following command in your terminal to create a new project using zkSync CLI. ``` npx zksync-cli create hello-zksync ``` It will give you options for different types of projects but for this tutorial choose the the following: ``` ? What type of project do you want to create? Contracts ? Template: Hardhat + Solidity ? Private key of the wallet responsible for deploying contracts (optional) *************************************************** ? Package manager: yarn ``` The project structure is pretty straight forward: * `hardhat.config.ts` contains the general configuration for Hardhat and the zkSync plugins, which are already imported and setup. * `/contracts` contains smart contracts. `zksync-cli` provides common examples like an ERC20, an NFT, and the Greeter contract that we'll use later on. * `/deploy` contains the deployment scripts. For this tutorial we'll focus on the `/contracts/Greeter.sol` contract: ``` //SPDX-License-Identifier: Unlicense pragma solidity ^0.8.0; contract Greeter { string private greeting; constructor(string memory _greeting) { greeting = _greeting; } function greet() public view returns (string memory) { return greeting; } function setGreeting(string memory _greeting) public { greeting = _greeting; } } ``` As you can see, it a simple Solidity contract with two methods to read a message, `greet()`, and modify it, `setGreeting()`. ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#compile-the-contract)Compile the contract Smart contracts deployed to zkLink Nova must be compiled using our custom compilers: * `zksolc` for Solidity contracts. * `zkvyper` for Vyper contracts. As this is a Solidity project, it already has the `hardhat-zksync-solc` plugin installed and configured so there's nothing you need to setup. To compile the contracts in the project, run the following command: yarn: ``` yarn compile ``` npm: ``` npm run compile ``` You'll get the following output: ``` Compiling contracts for zkSync Era with zksolc v1.3.21 and solc v0.8.17 Compiling 46 Solidity files Successfully compiled 46 Solidity files ✨ Done in 21.55s. ``` The compiled artifacts will be located in the `/artifacts-zk` folder. These artifacts are similar to the ones generated by the Solidity compiler. For example, the ABI of the Greeter contract will be located in `/artifacts-zk/contracts/Greeter.sol/Greeter.json`. The configuration for the `zksolc` compiler is located in the `zksolc` section of the `hardhat.config.ts` file. You can find more info about the compiler settings in the [hardhat-zksync-solc plugin](https://docs.zksync.io/build/tooling/hardhat/hardhat-zksync-solc.html) and the [compiler section](https://docs.zksync.io/zk-stack/components/compiler/specification/overview.html) of the ZK Stack documentation. ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#deploy-and-verify)Deploy and verify The project also contains a script to deploy and verify the contract in `/deploy/deploy.ts`. Under the hood, this script uses `hardhat-zksync-deploy` and `hardhat-zksync-verify` for deployment and contract verification. ``` import { deployContract } from "./utils"; // An example of a basic deploy script // It will deploy a Greeter contract to selected network // as well as verify it on Block Explorer if possible for the network export default async function () { const contractArtifactName = "Greeter"; const constructorArguments = ["Hi there!"]; await deployContract(contractArtifactName, constructorArguments); } ``` To execute it, just run: yarn: ``` yarn deploy ``` npm: ``` npm run deploy ``` You'll get the following output: ``` Starting deployment process of "Greeter"... Estimated deployment cost: 0.0000648863 ETH "Greeter" was successfully deployed: - Contract address: 0x0BaF96A7f137B05d0D35b76d59B16c86C1791D8D - Contract source: contracts/Greeter.sol:Greeter - Encoded constructor arguments: 0x000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000094869207468657265210000000000000000000000000000000000000000000000 Requesting contract verification... Your verification ID is: 1781 ``` Congratulations! You just deployed a smart contract to zkLink Nova testnet. You can find it in the [zkLink Sepolia Explorer ](https://sepolia.explorer.zklink.io)by searching the contract address. In addition, the deployment script verified the contract automatically so you can see the source code in the contract tab of the block explorer. ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#interact-with-the-contract)Interact with the contract The project also comes with a script to interact with the contract in `/deploy/interact.ts`. Add the address of the Greeter contract you just deployed in the `CONTRACT_ADDRESS` variable inside the `/deploy/interact.ts` file: ``` import * as hre from "hardhat"; import { getWallet } from "./utils"; import { ethers } from "ethers"; // Address of the contract to interact with const CONTRACT_ADDRESS = ""; if (!CONTRACT_ADDRESS) throw "⛔️ Provide address of the contract to interact with!"; // An example of a script to interact with the contract export default async function () { console.log(`Running script to interact with contract ${CONTRACT_ADDRESS}`); // Load compiled contract info const contractArtifact = await hre.artifacts.readArtifact("Greeter"); // Initialize contract instance for interaction const contract = new ethers.Contract( CONTRACT_ADDRESS, contractArtifact.abi, getWallet() // Interact with the contract on behalf of this wallet ); // Run contract read function const response = await contract.greet(); console.log(`Current message is: ${response}`); // Run contract write function const transaction = await contract.setGreeting("Hello people!"); console.log(`Transaction hash of setting new message: ${transaction.hash}`); // Wait until transaction is processed await transaction.wait(); // Read message after transaction console.log(`The message now is: ${await contract.greet()}`); } ``` As you can see, we're simply using `ethers` to interact with our contract. zkSync is EVM compatible so you can use existing tools and libraries like `Hardhat`, `ethers`, `web3.js`, and users can use their existing wallets like Metamask, Rabby or Zerion. To execute the `/deploy/interact.ts` script, run: yarn: ``` yarn interact ``` npm: ``` npm run interact ``` You'll get the following output: ``` Running script to interact with contract 0x0BaF96A7f137B05d0D35b76d59B16c86C1791D8D Current message is: Hi there! Transaction hash of setting new message: 0x7a534857cfcd6df7e3eaf40a79a2c88f2e36bb60ce6f2399345e5431362b04eb The message now is: Hello people! ✨ Done in 4.13s. ``` Congratulations! You've retrieved and updated the message on the `Greeter` contract. You can see the transaction in the [block explorer](https://sepolia.explorer.zklink.io) by searching the transaction hash. ### [#](https://docs.zksync.io/build/quick-start/hello-world.html#takeaways)Takeaways * zkLink Nova is EVM compatible and you can write smart contracts in Solidity or Vyper, use Hardhat, libraries like Ethers and Web3.js, or wallets like Metamask and Rabby. * zkLink Nova is built on top of [ZK Stack](https://docs.zksync.io/zk-stack), which leverages the underlying technology of zkSync. You could use the toolkit of zkSync to build your project. * zkSync CLI provides a quick way to scaffold different types of projects thanks to its multiple templates. * Contracts deployed to zkLink Nova are compiled using `zksolc` or `zkvyper` as they generate a special bytecode for zkSync's ZKEVM. * For more detailed information, you can refer to the [documentation of zkSync](https://docs.zksync.io/build/)