Foundry

This guide explains how to use Foundry with FHEVM for developing smart contracts.

While a Foundry template is currently in development, we strongly recommend using the Hardhat template for now, as it provides a fully tested and supported development environment for FHEVM smart contracts.

{% hint style="warning" %} Foundry does not natively support the FHEVM coprocessor. The mock-based approach described below does not replicate the full behavior of a real FHEVM node — encrypted operations run as plaintext stubs, so tests may pass locally but fail on a live network. {% endhint %}

If you still want to use Foundry, you can compile against a mocked version of the FHE library. To do this, change your FHE.sol imports from @fhevm/solidity/lib/FHE.sol to fhevm/mocks/FHE.sol in your Solidity source files.