Huff is a low-level programming language, designed for developing highly optimized smart contracts that run on the Ethereum Virtual Machine. Huff does not hide the inner-workings of the EVM, instead, directly exposing its programming stack to the developer for manual manipulation.

Rather than having functions, Huff has macros - individual blocks of bytecode that can be rigorously tested and evaluated using the Huff runtime testing suite.

Originally developed by the Aztec Protocol team, Huff was developed to write Weierstrudel, an on-chain eliptical curve arithmetic library that required code so optimized, that it could not be written in Solidity, or even Yul.

While Huff can be used by EVM experts to design highly-efficient smart contracts for use in production, it can also serve as a way for beginners to learn more about the Ethereum Virtual Machine, projects built on it, and languages made for it.

"Hello World" in Huff:

#define macro MAIN() = takes (0) returns (0) {
    0x48656c6c6f2c20776f726c6421 0x00 mstore // Store "Hello, World!" in memory.
    0x1a 0x00 return // Return 26 bytes starting from memory pointer 0.
}

To run this project, install it using npm

npm install -g huffc

To compile a contract and output its bytecode, simply run

huffc filename.huff --bytecode

For a full list of arguments, run

huffc --help