Deploy your first contract

This tutorial shows you how to deploy and interact with a smart contract on ZKsync Era in less than 5 minutes. It will help you get familiar with the ZKsync smart contract development and deployment process using different tools.

In this section you will learn how to:

Build a smart contract to exchange messages with Zeek.

Deploy the smart contract to the ZKsync Sepolia Testnet.

Interact with the contract from your browser using Remix.

Prerequisites

Before you start, make sure that you’ve configured the ZKsync Sepolia Testnet in your wallet.
Have at least 0.05 ZKsync Sepolia Testnet ETH. If you need more, use one of the faucets.

Review the smart contract code

The smart contract will store messages from users and emit events with replies from Zeek. The entire code is as follows:

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

contract ZeekMessages {
    string[] private messages;

    // Event to acknowledge a new message
    event MessageReceived(string);

    constructor() {
        // Zeek initializes the contract with a welcome message
        emit MessageReceived("Zeek welcomes you to ZKsync!");
    }

    function sendMessage(string memory _message) public {
        messages.push(_message);

        // Acknowledge the message receipt with Zeek's reply
        emit MessageReceived("ZK is the endgame - Message received!");
    }

    // Function to count the total messages sent to Zeek
    function getTotalMessages() public view returns (uint) {
        return messages.length;
    }

    // Function to return the last message sent to Zeek
    function getLastMessage() public view returns (string memory) {
        require(messages.length > 0, "No messages sent to Zeek yet!");
        return messages[messages.length - 1];
    }
}

The Solidity smart contract contains three functions:

sendMessage stores the messages sent by users in the messages state variable.
getTotalMessages returns the number of messages stored in the smart contract.
getLastMessage returns the last message sent.

Compile and deploy the contract

To compile and deploy the contract you can use either EVM or EraVM bytecode:

Learn more about using EraVM vs. EVM bytecode.

The Remix IDE is an open-source web and desktop application that supports Ethereum smart contract development and deployment, offering tools for writing, testing, debugging, and deploying smart contracts written in Solidity to EVM compatible protocols.

Clone the template project into Remix by clicking the "Clone" button on the "Home" tab under "Files". Then enter the repository URL below:

https://github.com/zkSync-Community-Hub/zksync-quickstart-remix.git

Then, open up the ZeekMessages.sol contract file.

Connect your wallet

On the left side menu bar, select the "Deploy & Run Transactions" tab. Click on the "Environment" dropdown menu, select "Customize this list...". Then, click the toggle icon to enable an injected wallet provider.

Connect wallet in Remix

Make sure your wallet is currently connected to the ZKsync Sepolia Testnet, as we will use our wallet’s configured network to deploy our smart contract.

Compile the contract

To compile the contract, click on the "Solidity Compiler" tab and press the "Compile ZeekMessages.sol" button.

Deploy the contract

To deploy the contract, go back to the "Deploy and run transactions" tab and click on the "Deploy" button. Sign the transaction in your wallet and wait a few seconds until it's processed. Congratulations, you’ve deployed your first contract to ZKsync Sepolia Testnet!

Remix interact ZKsync contract

Interact with the contract

Under "Deployed Contracts", click on your contract to show the interaction options:

Remix interact ZKsync contract

Write a message in the form, click the “sendMessage” button and confirm the transaction in your wallet. Once processed, click the getTotalMessages and check the response in the terminal, which should be 1. The getLastMessage function should also return the message you just sent. That means the contract is storing the messages as expected! But how can we see the replies from Zeek?

Check the contract in explorer

Copy the smart contract address from Remix and search it via the ZKsync Sepolia Testnet explorer. You’ll see the contract has a transaction from the message you just sent.

Contract in ZKsync explorer

The status will be “Processed” on ZKsync Era and “Sending” on Ethereum. Learn more about the transaction lifecycle on ZKsync.

In the “Contract” tab you’ll see the contract source code as the block explorer automatically partially verified the contract for us.

When a smart contract is verified in a block explorer, it means that the source code of the contract has been published and matched to the compiled version on the blockchain enhancing transparency, as users can review the contract’s source code to understand its functions and intentions.

Enable the Remix ZKsync plugin

To deploy EraVM bytecode smart contracts to ZKsync via Remix you need to enable the ZKsync plugin.

Visit the Remix website
Click on the “🔌 Plugin Manager” button in the bottom-left corner
Search “zksync” and click on the "Activate" button.

Enable ZKsync plugin in Remix

Once activated, you’ll see a new menu item with the ZKsync logo. Click on it to see the different options to compile, deploy, and interact with smart contracts on ZKsync.

Clone the template project into Remix by clicking the "Clone" button on the "Home" tab under "Files". Then enter the repository URL below:

https://github.com/zkSync-Community-Hub/zksync-quickstart-remix.git

Connect your wallet

In the ZKsync Remix plugin, under the Environment Section, select “Wallet” and click on “Connect Wallet” as shown below:

Connect wallet in Remix

Make sure your wallet is currently connected to the ZKsync Sepolia Testnet, as we will use our wallet’s configured network to deploy our smart contract.

Compile the contract

To compile the contract, open the ZeeksSecretMessages.sol file in the editor, go the ZKsync plugin, and click on "Compile ZeeksSecretMessages.sol". If you get a popup message requesting permissions to access ACCESS TO "WRITEFILE" OF "FILE MANAGER", click on "Accept".

Behind the scenes, Remix is using the ZKsync Era custom solidity compiler (named zksolc) to generate ZKsync VM compatible bytecode. Learn more about ZKsync custom compilers.

Deploy the contract

To deploy the contract, open the "Deploy" dropdown, check the "Verify contract" checkbox, and click on “Deploy & Verify”. Sign the transaction in your wallet and wait a few seconds until it's processed. Congratulations, you’ve deployed your first contract to ZKsync Sepolia Testnet!

Remix interact ZKsync contract

Interact with the contract

Next to the contract name you can find the address where the contract is deployed. The “Interact” section displays the forms to interact with the getTotalMessages and sendMessage functions.

Remix interact ZKsync contract

Check the contract in explorer

Copy the smart contract address from Remix and search it via the ZKsync Sepolia Testnet explorer. You’ll see the contract has a transaction from the message you just sent.

Contract in ZKsync explorer

The status will be “Processed” on ZKsync Era and “Sending” on Ethereum. Learn more about the transaction lifecycle on ZKsync.

In the “Contract” tab you’ll see the contract source code as Remix automatically verified the contract for us.

Finally in the “Events” tab, you’ll see the replies from Zeek as these are emitted as events in our smart contract.

Contract events in ZKsync explorer

ZK is the endgame ✌️

Takeaways

EVM-compatibility: ZKsync Era is EVM-compatible and you can write smart contracts in Solidity or Vyper as in Ethereum.
Custom compilers: smart contracts deployed to ZKsync Era can either be compiled as EVM using default compilers and tools, or EraVM with the custom compilers: zksolc for Solidity and zkvyper for Vyper.
Browser-based IDEs: You can use existing tools like Remix to deploy EVM or EraVM contracts.

Next steps

Continue learning by deploying an ERC20 token to ZKsync.
Join the ZKsync developer community in Discord where you can ask any questions about this tutorial in the #dev-quickstart channel.
Join our GitHub Discussions Community to help other devs building on ZKsync or share your project.

Overview

Learn how to interact with ZKsync Era

Create an ERC20 token

In this tutorial you'll build and deploy an ERC20 token to ZKsync Sepolia Testnet