Foundry vs Viem
A detailed head-to-head comparison of Foundry and Viem — pricing, features, and which one wins for different use cases.
Foundry
Blazing-fast Rust-based Solidity testing framework with built-in fuzzing and invariant testing
Foundry is a Rust-based Ethereum development toolkit built by Paradigm that has become the preferred framework for security-conscious and performance-focused Solidity teams. Its defining advantage ove…
Full review →Viem
Modern, type-safe TypeScript interface for Ethereum
Viem is a modern, lightweight, TypeScript-first library for interacting with Ethereum — a low-level interface for reading blockchain data, sending transactions, interacting with contracts, and more — …
Full review →Feature Comparison
| Feature | Foundry | Viem |
|---|---|---|
| Local Node | ✓ | ✗ |
| Mainnet Forking | ✓ | ✗ |
| Language | Solidity (tests) | TypeScript |
| Test Framework | forge-std | ✗ |
| Plugin Ecosystem | Growing (smaller than Hardhat) | ✓ |
| Debugging | ✓ | ✗ |
| Deployment System | Forge scripts | ✗ |
| Open Source | ✓ | ✓ |
| Fuzz Testing | ✓ | — |
| Invariant Testing | ✓ | — |
| Coverage Reporting | — | ✗ |
| Gas Reporting | — | ✗ |
Foundry Pricing
Foundry
Free (Open Source)
Free
- ✓forge, cast, anvil, chisel
- ✓Solidity tests
- ✓Built-in fuzzer
- ✓Invariant testing
- ✓Mainnet forking
- ✓Forge Standard Library
Viem Pricing
Viem
Free (Open Source)
Free
- ✓Type-safe Ethereum interface
- ✓Reads, writes, contract interaction
- ✓Foundation for Wagmi
- ✓Small, fast, modular
- ✓Full ABI type inference
Verdict: Which Should You Choose?
Foundry is the better pick if you need 5–20x faster test execution than hardhat — critical for large suites and audit pipelines. Viem wins when modern, type-safe alternative to ethers/web3.js. Both are production-ready — the right choice depends on your team's workflow and budget.