To use Foundry to build smart contracts on Abstract, use the foundry-zksync fork.

YouTube Tutorial: Get Started with Foundry

Watch a step-by-step tutorial on how to get started with Foundry.

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1. Install the foundry-zksync fork

This installation overrides any existing forge and cast binaries in ~/.foundry. To revert to the standard foundry installation, follow the Foundry installation guide. You can swap between the two installations at any time.

1

Install foundry-zksync

Install the foundryup-zksync fork:

curl -L https://raw.githubusercontent.com/matter-labs/foundry-zksync/main/install-foundry-zksync | bash

Run foundryup-zksync to install forge, cast, and anvil:

foundryup-zksync

You may need to restart your terminal session after installation to continue.

2

Verify installation

A helpful command to check if the installation was successful is:

forge build --help | grep -A 20 "ZKSync configuration:"

If installed successfully, 20 lines of --zksync options will be displayed.

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2. Create a new project

Create a new project with forge and change directory into the project.

forge init my-abstract-project && cd my-abstract-project

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3. Modify Foundry configuration

Update your foundry.toml file to include the following options:

[profile.default]
src = 'src'
libs = ['lib']
fallback_oz = true
is_system = false # Note: NonceHolder and the ContractDeployer system contracts can only be called with a special isSystem flag as true
mode = "3"

To use system contracts, set the is_system flag to true.

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4. Write a smart contract

Modify the src/Counter.sol file to include the following smart contract:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract Counter {
    uint256 public number;

    function setNumber(uint256 newNumber) public {
        number = newNumber;
    }

    function increment() public {
        number++;
    }
}

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5. Compile the smart contract

Use the zksolc compiler (installed in the above steps) to compile smart contracts for Abstract:

forge build --zksync

You should now see the compiled smart contracts in the generated zkout directory.

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6. Deploy the smart contract

Get testnet funds

Deploying smart contracts requires testnet ETH.

Claim testnet funds via a faucet, or bridge ETH from Sepolia to the Abstract testnet.

Add your private key

Create a new wallet keystore.

cast wallet import myKeystore --interactive

Enter your wallet’s private key when prompted & provide a password to encrypt it.

We recommend not to use a private key associated with real funds. Create a new wallet for this step.

Deploy your smart contract

Run the following command to deploy your smart contracts:

forge create src/Counter.sol:Counter \
    --account myKeystore \
    --rpc-url https://api.testnet.abs.xyz \
    --chain 11124 \
    --zksync

Ensure myKeystore is the name of the keystore file you created in the previous step.

If successful, the output should look similar to the following:

Deployer: 0x9C073184e74Af6D10DF575e724DC4712D98976aC
Deployed to: 0x85717893A18F255285AB48d7bE245ddcD047dEAE
Transaction hash: 0x2a4c7c32f26b078d080836b247db3e6c7d0216458a834cfb8362a2ac84e68d9f

Verify your smart contract on the block explorer

Verifying your smart contract is helpful for others to view the code and interact with it from a block explorer. To verify your smart contract, run the following command:

forge verify-contract 0x85717893A18F255285AB48d7bE245ddcD047dEAE \
    src/Counter.sol:Counter \
    --verifier etherscan \
    --verifier-url https://api-sepolia.abscan.org/api \
    --etherscan-api-key TACK2D1RGYX9U7MC31SZWWQ7FCWRYQ96AD \
    --zksync

Note: Replace the contract path and address with your own.

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