Foundry

Foundry is an open-source toolkit for Ethereum and EVM-compatible smart contract development. It is best known for Forge, which compiles and tests contracts, Cast, which interacts with blockchains from the command line, and Anvil, a local test network for development. Unlike some JavaScript-based frameworks, Foundry is written in Rust and is often used with Solidity tests, meaning developers can write tests in the same language as their contracts.

Foundry matters because it helps developers catch bugs, simulate transactions, and automate deployments before code reaches a live blockchain, where mistakes can be costly and difficult to reverse. For example, a developer building a token contract might use Forge to run unit tests, Anvil to test the contract locally, and Cast to query balances or send transactions on a testnet. It is commonly compared with Hardhat: both are popular smart contract development environments, but Foundry is especially associated with speed, command-line workflows, and Solidity-native testing.