What languages are smart contracts written in?

#The chain runs bytecode, not source

Ethereum does not understand Solidity, or any human-readable language. It runs the Ethereum Virtual Machine, a simple processor that executes low-level instructions called opcodes. A programming language is a comfortable way to write those instructions; a compiler turns your source into the bytecode that actually gets deployed. This matters for two reasons: any language that compiles to EVM bytecode works on Ethereum, and what an auditor ultimately reasons about is the compiled behaviour, not the pretty source.

#Solidity, the default

The overwhelming majority of Ethereum contracts are written in Solidity. Its syntax borrows from C and JavaScript, so it feels familiar, and it has the deepest ecosystem: the most libraries, the most tooling, the most auditors, and the most example code to learn from. If you read one language in this space, read this one; every other guide in this section uses it.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract Greeter {
    string public greeting = "gm";

    function setGreeting(string calldata g) external {
        greeting = g;
    }
}

#Vyper, Yul, and assembly

Vyper is the notable alternative on Ethereum. It looks like Python and is deliberately minimal: it leaves out features such as inheritance and function overloading on the theory that fewer moving parts means fewer places to hide a bug. Some security-focused projects prefer it for exactly that reason. The same contract above, in Vyper, reads like this.

# the same idea, Python-flavoured
greeting: public(String[32])

@external
def set_greeting(g: String[32]):
    self.greeting = g

Below both sits Yul, an intermediate language, and inline assembly, which lets a Solidity author drop down to raw EVM opcodes inside a function. These are used sparingly, to squeeze out gas or to do something the high-level language forbids. They are also where subtle bugs love to live, because the safety checks the compiler normally adds are exactly what you are stepping around.

#Beyond Ethereum

Other blockchains run different virtual machines and so use different languages. Solana and NEAR contracts are commonly written in Rust. Aptos and Sui use Move, a language designed around safely representing digital assets so they cannot be accidentally copied or lost. The syntax and the tooling differ, but the mental model carries over cleanly: a program deployed on-chain, holding state, called by transactions, spending a fee to run. Learn the pattern once and each new chain is mostly a change of dialect.