Developer Quickstart - ZKsync Docs

You can use all standard EVM tooling for ZKsync OS. You can find instructions for bridging testnet ETH to ZKsync OS Developer Preview testnet in the Network Details page.

To get started with Foundry or Hardhat, follow the steps below:

Create a new foundry project:
```
forge init Counter
```
```
cd Counter
```
Build the project
```
forge build
```
Set your private key for deploying:
```
export TESTNET_PRIVATE_KEY="0x..."
```

Deploy the contract:

forge script script/Counter.s.sol --rpc-url https://zksync-os-testnet-alpha.zksync.dev --broadcast --skip-simulation --private-key $TESTNET_PRIVATE_KEY

Set the number value:

cast send 0x<YOUR_CONTRACT_ADDRESS> \
"setNumber(uint256)" 5 \
--rpc-url https://zksync-os-testnet-alpha.zksync.dev \
--private-key $TESTNET_PRIVATE_KEY

Get the latest number value:

cast call 0x<YOUR_CONTRACT_ADDRESS> \
"number()" \
--rpc-url https://zksync-os-testnet-alpha.zksync.dev

Verify the contract:

forge verify-contract \
--chain-id 8022833 \
--verifier custom \
--verifier-url https://block-explorer-api.zksync-os-testnet-alpha.zksync.dev/api \
0x<YOUR_CONTRACT_ADDRESS> \
src/Counter.sol:Counter

Create a new project folder

mkdir hardhat-example
cd hardhat-example

Initialize a new Hardhat 3 project with Node Test Runner and Viem.
```
npx hardhat --init
```

Add ZKsync OS to the hardhat.config.ts file and configure the ignition required confirmations.

hardhat.config.ts

  ignition: {
    requiredConfirmations: 1,
  },
  networks: {
    zksyncOS: {
      type: 'http',
      chainType: 'generic',
      url: 'https://zksync-os-testnet-alpha.zksync.dev',
      accounts: [configVariable('TESTNET_PRIVATE_KEY')],
    },
  },

Add your private key to the keystore as TESTNET_PRIVATE_KEY.
```
npx hardhat keystore set TESTNET_PRIVATE_KEY
```
Compile and deploy the example contract.
```
npx hardhat compile
```
```
npx hardhat ignition deploy ignition/modules/Counter.ts --network zksyncOS
```
Create a new script file in the scripts folder called increment.ts.
```
touch scripts/increment.ts
```

Copy/paste the script below.

increment.ts

import { network } from 'hardhat';
import { type Abi, defineChain } from 'viem';

const CONTRACT_ADDRESS = '0x7Be3f2d08500Fe75B92b9561287a16962C697cb7';

const { viem } = await network.connect('zksyncOS');

const zksyncOS = defineChain({
  id: 8022833,
  name: 'ZKsync OS',
  network: 'zksyncOS',
  nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
  rpcUrls: { default: { http: ['https://zksync-os-testnet-alpha.zksync.dev'] } },
});

const publicClient = await viem.getPublicClient({ chain: zksyncOS });
const [senderClient] = await viem.getWalletClients({ chain: zksyncOS });
if (!senderClient) throw new Error('No wallet client. Set TESTNET_PRIVATE_KEY in hardhat config.');

const counterContract = await viem.getContractAt('Counter', CONTRACT_ADDRESS, {
  client: { public: publicClient, wallet: senderClient },
});

const initialCount = await publicClient.readContract({
  address: CONTRACT_ADDRESS,
  abi: counterContract.abi as Abi,
  functionName: 'x',
});
console.log('Initial count:', initialCount);

const tx = await senderClient.writeContract({
  address: CONTRACT_ADDRESS,
  abi: counterContract.abi as Abi,
  functionName: 'inc',
});
await publicClient.waitForTransactionReceipt({ hash: tx });
console.log('Transaction sent successfully');

const newCount = await publicClient.readContract({
  address: CONTRACT_ADDRESS,
  abi: counterContract.abi as Abi,
  functionName: 'x',
});
console.log('New count:', newCount);

Run the script
```
npx hardhat run scripts/increment.ts
```

Install the Hardhat verify SDK:

npm install --save-dev @nomicfoundation/hardhat-verify

Add hardhatVerify to the hardhat plugins and configure the verification endpoint:

hardhat.config.ts

import hardhatVerify from "@nomicfoundation/hardhat-verify";

const config: HardhatUserConfig = {
plugins: [
    hardhatVerify,
    // ...other plugins...
],
// ...other config...
  chainDescriptors: {
    8022833: {
      name: 'zksyncOS',
      blockExplorers: {
        blockscout: {
          name: 'Testnet Explorer',
          url: 'https://zksync-os-testnet-alpha.staging-scan-v2.zksync.dev',
          apiUrl: 'https://block-explorer-api.zksync-os-testnet-alpha.zksync.dev/api',
        },
      },
    },
  },
};

Use your deployed contract address to verify using hardhat-verify:
```
npx hardhat verify --network zksyncOS 0x<YOUR_CONTRACT_ADDRESS>
```

Create a new project folder

mkdir hardhat-example
cd hardhat-example

Initialize a new Hardhat 3 project with Mocha and Ethers.js.
```
npx hardhat --init
```

Add ZKsync OS to the hardhat.config.ts file and configure the ignition required confirmations.

hardhat.config.ts

  ignition: {
    requiredConfirmations: 1,
  },
  networks: {
    zksyncOS: {
      type: 'http',
      chainType: 'generic',
      url: 'https://zksync-os-testnet-alpha.zksync.dev',
      accounts: [configVariable('TESTNET_PRIVATE_KEY')],
    },
  },

Add your private key to the keystore as TESTNET_PRIVATE_KEY.
```
npx hardhat keystore set TESTNET_PRIVATE_KEY
```
Compile and deploy the example contract.
```
npx hardhat compile
```
```
npx hardhat ignition deploy ignition/modules/Counter.ts --network zksyncOS
```
Create a new script file in the scripts folder called increment.ts.
```
touch scripts/increment.ts
```

Copy/paste the script below.

increment.ts

import { network } from 'hardhat';

const CONTRACT_ADDRESS = '0x8e882b31Fe1d3942c57408D354E754d1659400a7';

const { ethers } = await network.connect({
  network: 'zksyncOS',
  chainType: 'generic',
});

const [sender] = await ethers.getSigners();

const contract = await ethers.getContractAt('Counter', CONTRACT_ADDRESS, sender);

const initialCount = await contract.x();
console.log('Initial count:', initialCount);

const tx = await contract.inc();
await tx.wait();
console.log('Transaction sent successfully');

const newCount = await contract.x();
console.log('New count:', newCount);

Run the script
```
npx hardhat run scripts/increment.ts
```

Install the Hardhat verify SDK:

npm install --save-dev @nomicfoundation/hardhat-verify

Add hardhatVerify to the hardhat plugins and configure the verification endpoint:

hardhat.config.ts

import hardhatVerify from "@nomicfoundation/hardhat-verify";

const config: HardhatUserConfig = {
plugins: [
    hardhatVerify,
    // ...other plugins...
],
// ...other config...
  chainDescriptors: {
    8022833: {
      name: 'zksyncOS',
      blockExplorers: {
        blockscout: {
          name: 'Testnet Explorer',
          url: 'https://zksync-os-testnet-alpha.staging-scan-v2.zksync.dev',
          apiUrl: 'https://block-explorer-api.zksync-os-testnet-alpha.zksync.dev/api',
        },
      },
    },
  },
};

Use your deployed contract address to verify using hardhat-verify:
```
npx hardhat verify --network zksyncOS 0x<YOUR_CONTRACT_ADDRESS>
```

Network Details

Connect to ZKsync OS Developer Preview testnet

FAQs

Answers to frequently asked questions about ZKsync OS.