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Why We Chose Foundry Over Hardhat

We started with Hardhat, like most Solidity developers. It works. The plugin ecosystem is mature. The TypeScript integration is solid. But after 6 months of shipping production contracts, we switched to Foundry — and we're not going back.

Here's the honest comparison, based on real production use across 4 deployed protocols.

Speed: It's Not Close

Hardhat compiles contracts through the Solidity compiler, then runs tests through Mocha + TypeScript. Foundry compiles and runs everything in Rust. The difference is dramatic:

• Hardhat: Full test suite for Tasklync took ~45 seconds
• Foundry: Same suite takes ~3 seconds

When you're running tests hundreds of times per day during development, that 15x speedup compounds into real productivity gains. Our CI pipeline went from 4 minutes to 20 seconds.

Tests in Solidity, Not JavaScript

This is the biggest workflow improvement. In Hardhat, you write tests in TypeScript — which means you're constantly context-switching between two languages. In Foundry, tests are written in Solidity:

Want to test that createJob reverts when the payment is zero? In Foundry, you write that assertion in Solidity, using the same types, same syntax, same mental model as the contract itself. No type mismatches between JS BigNumber and Solidity uint256. No ethers.parseEther() boilerplate. Just Solidity.

Built-In Fuzzing

Foundry ships with forge test --fuzz-runs 10000 out of the box. No plugins, no configuration. Every test function with parameters automatically becomes a fuzz test. Foundry generates random inputs and runs your assertion against all of them.

This caught a reentrancy vulnerability in our escrow contract that would have passed a manual audit and a standard unit test. The fuzzer found input combinations that triggered the bug in seconds. Hardhat can do fuzzing with plugins, but it's clunky and slow — we never used it in practice. With Foundry, fuzzing is just how tests work.

What Hardhat Still Does Better

To be fair: Hardhat's console.log debugging is excellent. Foundry's equivalent (forge test -vvvv) shows traces but isn't as intuitive. Hardhat's plugin ecosystem (gas reporter, contract sizer, etc.) is significantly more mature. And if your team is primarily TypeScript developers, the learning curve for Solidity-native testing is real.

But for a team shipping production contracts to mainnet? Foundry's speed, safety, and simplicity win. Every time.