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Foundry consists of:

• Forge: Build, test, fuzz, debug and deploySolidity contracts, like Hardhat, Brownie, Ape.
• Cast: A Swiss Army knife for interacting with EVM smart contracts, sending transactions and getting chain data.
• Anvil: Fast local Ethereum development node, akin to Hardhat Network, Tenderly.
• Chisel: Fast, utilitarian, and verbose Solidity REPL.

Need help getting started with Foundry? Read the📖 Foundry Book!

• High-Performance Compilation

  • Fast and Flexible: Automatically detects and installs the required Solidity compiler version.
  • Solidity and Vyper Support: Fully supports both Solidity and Vyper out-of-the-box.
  • Incremental Compilation: Re-compiles only changed files, saving time.
  • Parallelized Pipeline: Leverages multi-core systems for ultra-fast builds.
  • Broad Compatibility: Supports non-standard directory structures, includingHardhat repos.

• Advanced Testing

  • No Context Switching: Write tests directly in Solidity.
  • Fuzz Testing: Quickly identify edge cases with input shrinking and counter-example generation.
  • Invariant Testing: Ensure complex system properties hold across a wide range of inputs.
  • Debugging Made Easy: Useforge-std'sconsole.sol for flexible debug logging.
  • Interactive Debugger: Step through your Solidity code with Foundry's interactive debugger, making it easy to pinpoint issues.

• Powerful Runtime Features

  • RPC Forking: Fast and efficient remote RPC forking backed byAlloy.
  • Lightweight & Portable: No dependency on Nix or other package managers for installation.

• Streamlined CI/CD

  • Optimized CI: Accelerate builds, run tests and execute scripts usingFoundry's GitHub action.

Getting started is very easy:

Installfoundryup:

curl -L https://foundry.paradigm.xyz | bash

Next, runfoundryup.

It will automatically install the latest version of the precompiled binaries:forge,cast,anvil, andchisel.

foundryup

Done!

For additional details see theinstallation guide in theFoundry Book.

If you're experiencing any issues while installing, check outGetting Help and theFAQ.

Forge is quite fast at both compiling (leveragingsolc withfoundry-compilers) and testing.

See the benchmarks below. Older benchmarks againstDappTools can be found in thev0.2.0 announcement post and in theConvex Shutdown Simulation repository.

In the above benchmarks, compilation was always skipped

Takeaway: Forge dramatically outperforms the competition, delivering blazing-fast execution speeds while continuously expanding its robust feature set.

 

Takeaway: Forge compilation is consistently faster than Hardhat by a factor of2.1x to5.2x, depending on the amount of caching involved.

Forge helps you build, test, fuzz, debug and deploy Solidity contracts.

The best way to understand Forge is to simply try it (in less than 30 seconds!).

First, let's initialize a newcounter example repository:

forge init counter

Nextcd intocounter and build :

forge build

[⠊] Compiling...[⠔] Compiling 27 files with Solc 0.8.28[⠒] Solc 0.8.28 finished in 452.13msCompiler run successful!

Let'stest our contracts:

forgetest

[⠊] Compiling...No files changed, compilation skippedRan 2 tests for test/Counter.t.sol:CounterTest[PASS] testFuzz_SetNumber(uint256) (runs: 256, μ: 31121, ~: 31277)[PASS] test_Increment() (gas: 31293)Suite result: ok. 2 passed; 0 failed; 0 skipped; finished in 5.35ms (4.86ms CPU time)Ran 1 test suite in 5.91ms (5.35ms CPU time): 2 tests passed, 0 failed, 0 skipped (2 total tests)

Finally, let's run our deployment script:

forge script script/Counter.s.sol

[⠊] Compiling...No files changed, compilation skippedScript ran successfully.Gas used: 109037If you wish to simulate on-chain transactions pass a RPC URL.

Runforge --help to explore the full list of available subcommands and their usage.

More documentation can be found in theforge section of the Foundry Book.

Cast is a Swiss Army knife for interacting with Ethereum applications from the command line.

Here are a few examples of what you can do:

Check the latest block on Ethereum Mainnet:

cast block-number --rpc-url https://eth.merkle.io

Check the Ether balance ofvitalik.eth

cast balance vitalik.eth --ether --rpc-url https://eth.merkle.io

Replay and trace a transaction

cast run 0x9c32042f5e997e27e67f82583839548eb19dc78c4769ad6218657c17f2a5ed31 --rpc-url https://eth.merkle.io

Optionally, pass--etherscan-api-key <API_KEY> to decode transaction traces using verified source maps, providing more detailed and human-readable information.

Runcast --help to explore the full list of available subcommands and their usage.

More documentation can be found in thecast section of the Foundry Book.

Anvil is a fast local Ethereum development node.

Let's fork Ethereum mainnet at the latest block:

anvil --fork-url https://eth.merkle.io

You can use those samecast subcommands against youranvil instance:

cast block-number

Runanvil --help to explore the full list of available features and their usage.

More documentation can be found in theanvil section of the Foundry Book.

Chisel is a fast, utilitarian, and verbose Solidity REPL.

To use Chisel, simply typechisel.

chisel

From here, start writing Solidity code! Chisel will offer verbose feedback on each input.

Create a variablea and query it:

➜uint256 a = 123;➜aType: uint256├ Hex: 0x7b├ Hex (full word): 0x000000000000000000000000000000000000000000000000000000000000007b└ Decimal: 123

Finally, run!source to seea was applied:

// SPDX-License-Identifier: UNLICENSEDpragma solidity^0.8.28;import {Vm}from"forge-std/Vm.sol";contractREPL {    Vminternalconstant vm=Vm(address(uint160(uint256(keccak256("hevm cheat code")))));/// @notice REPL contract entry pointfunction run()public {uint256 a=123;    }}

Runchisel --help to explore the full list of available features and their usage.

More documentation can be found in thechisel section of the Foundry Book.

Foundry is highly configurable, allowing you to tailor it to your needs. Configuration is managed via a file calledfoundry.toml located in the root of your project or any parent directory. For a full list of configuration options, refer to theconfig package documentation.

Profiles and Namespaces

• Configuration can be organized intoprofiles, which are arbitrarily namespaced for flexibility.
• The default profile is nameddefault. Learn more in theDefault Profile section.
• To select a different profile, set theFOUNDRY_PROFILE environment variable.
• Override specific settings using environment variables prefixed withFOUNDRY_ (e.g.,FOUNDRY_SRC).

You can find additionalsetup and configurations guides in theFoundry Book and in theconfig crate:

• Configuring withfoundry.toml
• Setting up VSCode
• Shell autocompletions

See ourcontributing guidelines.

First, see if the answer to your question can be found in theFoundy Book, or in the relevant crate.

If the answer is not there:

• Join thesupport Telegram to get help, or
• Open adiscussion with your question, or
• Open an issue withthe bug

If you want to contribute, or follow along with contributor discussion, you can use ourmain telegram to chat with us about the development of Foundry!

Licensed under either ofApache License, Version2.0 orMIT License at your option.

Unless you explicitly state otherwise, any contribution intentionally submittedfor inclusion in these crates by you, as defined in the Apache-2.0 license,shall be dual licensed as above, without any additional terms or conditions.

• Foundry is a clean-room rewrite of the testing frameworkDappTools. None of this would have been possible without the DappHub team's work over the years.
• Matthias Seitz: Createdethers-solc (nowfoundry-compilers) which is the backbone of our compilation pipeline, as well as countless contributions to ethers, in particular theabigen macros.
• Rohit Narurkar: Created the Rust Solidity version managersvm-rs which we use to auto-detect and manage multiple Solidity versions.
• Brock Elmore: For extending the VM's cheatcodes and implementingstructured call tracing, a critical feature for debugging smart contract calls.
• All the othercontributors to theethers-rs,alloy &foundry repositories and chatrooms.