#Integrating with Foundry

This guide explains how to combine Hardhat and Foundry in the same project using our @nomicfoundation/hardhat-foundry plugin.

# Setting up a hybrid project

How to set up a project that combines Hardhat and Foundry depends on whether you have an existing Hardhat project or an existing Foundry project.

#Adding Foundry to a Hardhat project

If you have an existing Hardhat project and you want to use Foundry in it, you should follow these steps.

First, run forge --version to make sure that you have Foundry installed. If you don't, go here to get it.

After that, install the @nomicfoundation/hardhat-foundry plugin:

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

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

yarn add --dev @nomicfoundation/hardhat-foundry

pnpm add --save-dev @nomicfoundation/hardhat-foundry

and import it in your Hardhat config:

import "@nomicfoundation/hardhat-foundry";

require("@nomicfoundation/hardhat-foundry");

To complete the setup, run npx hardhat init-foundry. This task will create a foundry.toml file with the right configuration and install forge-std.

#Adding Hardhat to a Foundry project

If you have an existing Foundry project and you want to use Hardhat in it, follow these steps.

First, if you don't have a package.json already in your project, create one with npm init.

Then install Hardhat, the Hardhat Toolbox, and the @nomicfoundation/hardhat-foundry plugin:

npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-foundry

npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-foundry

yarn add --dev hardhat @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-foundry

pnpm add --save-dev hardhat @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-foundry

After that, initialize a Hardhat project with npx hardhat init. Choose the "Create an empty hardhat.config.js" option, and then import the plugin in hardhat.config.js:

require("@nomicfoundation/hardhat-toolbox");
require("@nomicfoundation/hardhat-foundry");

You should now be able to compile your project with Hardhat and to add Hardhat scripts and tests.

# Working with a combined setup

Once you've set up a project as explained in the previous section, you'll be able to use both Hardhat and Foundry in it. These are some of the things you can do:

• Write some tests in JavaScript/TypeScript and run them with npx hardhat test
• Write other tests in Solidity and run them with forge test
• Compile your contracts with either npx hardhat compile or forge build
• Write a custom Hardhat task and execute it

Check our docs and Foundry docs to learn more.