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Deploy with Solidity


This article shows how to deploy a Solidity smart contract using Hardhat on any of Quai Network's chains. For more complex deployments involving SolidityX and multi-chain deployments, visit the Deploy with SolidityX Tutorial.


To deploy single chain smart contracts on Quai, we'll need a few tool-kits and dependencies.

Here's an overview of all of the dependencies we'll be using:

  • NodeJS: Javascript runtime environment. Use the LTS version.
  • Quai Network hardhat-example: A simple Hardhat project with sample contracts and deploy scripts.

Environment Setup


Start by cloning the hardhat-example repository, navigating to the Solidity directory we'll be using for this tutorial, and installing the dependencies via npm.

git clone
cd hardhat-example/Solidity
npm install

Smart Contracts

The Solidity directory comes with 2 sample contracts: ERC20.sol and ERC721.sol inside of the contracts/ directory. Both contracts are implementations derived from the Open Zeppelin library.

We'll be using the ERC20.sol sample contract for this tutorial, but you can also add your own contracts or use contracts from other libraries.

Environment Variables

We've included a sample environment file, .env.dist, file at the root of the hardhat-example repo to manage token details, private keys, and RPC URLs in a secure fashion.


The .env.dist file is a template file and should not be used as is. You should copy the .env.dist file to a new .env file in the repository root using the following command:

This file lives at the root of the hardhat-example repository and serves as the config file for both the Solidity and SolidityX directories.

Copy the .env.dist file in the root to a new .env file in the repository root using the following command:

cp ../.env.dist ../.env

Open the .env file and add your private keys, RPC URLs, and token args for the contract you'd like to deploy. The .env file should look like this:

# Unique Privkey for each deployment address
CYPRUS1PK="0x3700000000000000000000000000000000000000000000000000000000000000" # For pubkey starting with 0x00 - 0x1D
CYPRUS2PK="0x9400000000000000000000000000000000000000000000000000000000000000" # For pubkey starting with 0x1E - 0x3A
...more priv keys

# Chain ID (local: 1337, testnet: 9000, devnet: 12000)

# RPC endpoints
...more rpc urls

# Token Arguments
...more token args

The PRIVKEY values must all be for unique addresses and correspond to the chain name, i.e. your CYPRUS1PK should be the private key of your Cyprus-1 address.

All of the RPCURL values have already been filled in for you, but you can change them to your own RPC URLs if you're running your own nodes.

Further information on RPC endpoints can be found in the local network specifications section for local nodes and the testnet specifications section for remote nodes.

After filling in your private keys, RPC URLs, we're now ready to securely consume them inside of hardhat.config.js.

Hardhat Configuration

Hardhat uses hardhat.config.js to configure smart contract deployments. The config file allows you to define deployment networks, tasks, compilers, etc.

hardhat-example contains a prebuilt hardhat.config.js file with configurations for deploying and verifying smart contracts on any shard in the network.

The file should look like this:

* @type import('hardhat/config').HardhatUserConfig

const dotenv = require("dotenv");
dotenv.config({ path: "../.env" });

module.exports = {
defaultNetwork: "cyprus1",
networks: {
cyprus1: {
url: `${process.env.CYPRUS1URL}`,
accounts: [process.env.CYPRUS1PK],
chainId: Number(process.env.CHAINID),
cyprus2: {
url: `${process.env.CYPRUS2URL}`,
accounts: [process.env.CYPRUS2PK],
chainId: Number(process.env.CHAINID),
...more networks

solidity: {
version: "0.8.20",
settings: {
optimizer: {
enabled: true,
runs: 1000,

etherscan: {
apiKey: {
cyprus1: "abc",
...more api keys
customChains: [
network: "cyprus1",
chainId: Number(process.env.CHAINID),
urls: {
apiURL: "",
browserURL: "",
...more verification configs

Inside the config file you can find deployment and verification definitions for:

  • cyprus1
  • cyprus2
  • cyprus3
  • paxos1
  • paxos2
  • paxos3
  • hydra1
  • hydra2
  • hydra3

When deploying or verifying a contract, hardhat.config.js will pull your private keys and RPC URLs from the .env file and use them to deploy and verify your contracts. You can also specify the Solidity version and compiler settings in the solidity object.


Compile with Hardhat

Smart contract compilation with Hardhat is simple and can be done using npx in the CLI.

Compile all of the contracts inside the contracts/ directory with:

npx hardhat compile

Which should output:

Downloading compiler 0.8.20

Compiled 2 Solidity files successfully

Deployment Scripts

Inside the scripts/ directory, you'll find a deploy script for both ERC20.sol and ERC721.sol: deployERC20.js and deployERC721.js. For this tutorial, we'll be using deployERC20.js.

The deployERC20.js script pulls your network configuration from hardhat.config.js and your token arguments from the .env file at the root of the repository and uses them to deploy your contract.

Token arguments are consumed via the tokenArgs object:

tokenArgs = {
name: process.env.ERC20_NAME, // Name of token
symbol: process.env.ERC20_SYMBOL, // Symbol of token
initialSupply: process.env.ERC20_INITIALSUPPLY, // Initial supply of token, will be minted to deployer

Your specified network configuration is consumed inside of the provider and wallet variables in tandem with the compiled contract ABI and bytecode to create a new contract instance:

const provider = new quais.providers.JsonRpcProvider(;
const wallet = new quais.Wallet([0], provider);
const ERC20 = new quais.ContractFactory(ERC20Json.abi, ERC20Json.bytecode, wallet);

We'll use these ideas to properly modify the token args and network specification to deploy our contract in the next step.


The deployERC721.js script functions in a similar manner, but with different contract arguments and a different contract ABI and bytecode. You can replicate this configuration for any contract you'd like to deploy.

Deploy Your Contract

The deploy script takes in a --network flag to specify the network you'd like to deploy to (available options can be found here). For this tutorial, we'll be deploying to cyprus1.

npx hardhat run scripts/deployERC20.js --network cyprus1

Which should output:

1 -- Deploy transaction broadcasted: 0x235fdeb85db5b6cee8da9780e2246907e8342751849f5ce3514847a5dffd916f
2 -- Waiting for transaction to be mined.
3 -- Transaction mined. ERC20 deployed to: 0x13d8c5fc0AB5A87870353f3C0409c102f2a772A9
-- Gas used: 249168

Congratulations, you've now deployed a ERC20 token to Quai Network!


The ERC20.sol and ERC721.sol sample contracts are basic implementations of each token for example purposes. It is highly recommended to modify these contracts to fit your specific use case before deploying them for any production use.

Interact with a Smart Contract

Hardhat console does not currently offer support for interaction with smart contracts on Quai Network. In order to interact with your smart contract, you'll need to utilize the the client JSON RPC or quais.js library. You can find quais examples in the quais-by-example repository.


Now you have all the tools you need to create a simple Hardhat project, deploy, and interact with your own smart contracts.