evmole 0.8.4

Extracts function selectors and arguments from EVM bytecode

EVMole is a powerful library that extracts information from Ethereum Virtual Machine (EVM) bytecode, including function selectors, arguments, state mutability, and storage layout, even for unverified contracts.

Key Features

• Multi-language support: Available as JavaScript, Rust, Python, and Go libraries.
• High accuracy and performance: Outperforms existing tools.
• Broad compatibility: Tested with both Solidity and Vyper compiled contracts.
• Lightweight: Clean codebase with minimal external dependencies.
• Unverified contract analysis: Extracts information even from unverified bytecode.

Usage

JavaScript

API documentation and usage examples (node, vite, webpack, parcel, esbuild)

$ npm i evmole

import { contractInfo } from 'evmole'

const code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'

console.log( contractInfo(code, {selectors:true, arguments:true, stateMutability:true}) )
// {
//   functions: [
//     {
//       selector: '2125b65b',
//       bytecodeOffset: 52,
//       arguments: 'uint32,address,uint224',
//       stateMutability: 'pure'
//     },
//     ...

Rust

Documentation is available on docs.rs

let code = hex::decode("6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256").unwrap();

println!("{:?}", evmole::contract_info(
    evmole::ContractInfoArgs::new(&code)
        .with_selectors()
        .with_arguments()
        .with_state_mutability()
    )
);
// Contract {
//     functions: Some([
//         Function {
//             selector: [33, 37, 182, 91],
//             bytecode_offset: 52,
//             arguments: Some([Uint(32), Address, Uint(224)]),
//             state_mutability: Some(Pure)
//         },
//         ...

Python

API documentation

$ pip install evmole --upgrade

from evmole import contract_info

code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'

print( contract_info(code, selectors=True, arguments=True, state_mutability=True) )
# Contract(
#     functions=[
#     Function(
#             selector=2125b65b,
#             bytecode_offset=52,
#             arguments=uint32,address,uint224,
#             state_mutability=pure),
#     ...

Go

API documentation

$ go get github.com/cdump/evmole/go

package main

import (
    "context"
    "encoding/hex"
    "fmt"

    "github.com/cdump/evmole/go"
)

func main() {
    code, _ := hex.DecodeString("6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256")

    info, _ := evmole.ContractInfo(context.Background(), code, evmole.Options{
        Selectors:       true,
        Arguments:       true,
        StateMutability: true,
    })

    for _, fn := range info.Functions {
        fmt.Printf("%s: %s @ %d\n", fn.Selector, *fn.Arguments, fn.BytecodeOffset)
    }
    // 2125b65b: uint32,address,uint224 @ 52
    // b69ef8a8:  @ 68
}

Foundry

Foundry's cast uses the Rust implementation of EVMole

$ cast selectors $(cast code 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2)
0x06fdde03                           view
0x095ea7b3  address,uint256          nonpayable
0x18160ddd                           view
0x23b872dd  address,address,uint256  nonpayable
...

$ cast selectors --resolve $(cast code 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2)
0x06fdde03                           view        name()
0x095ea7b3  address,uint256          nonpayable  approve(address,uint256)
0x18160ddd                           view        totalSupply()
0x23b872dd  address,address,uint256  nonpayable  transferFrom(address,address,uint256)
...

Benchmark

function selectors

FP/FN - False Positive/False Negative errors; smaller is better

Dataset		evmole rs · js · py · go	whatsabi	sevm	evmhound	heimdall
largest1k 1000 addresses 24427 functions	FP addrs	1 🥈	0 🥇	0 🥇	75	18
	FN addrs	0 🥇	0 🥇	0 🥇	40	103
	FP funcs	192 🥈	0 🥇	0 🥇	720	600
	FN funcs	0 🥇	0 🥇	0 🥇	191	114
	Time	18ms · 0.2s · 22ms · 69ms	2.3s	30s(*)	56ms	371s(*)
random50k 50000 addresses 1171102 functions	FP addrs	1 🥇	43	1	693	3
	FN addrs	9 🥇	11	10	2903	4669
	FP funcs	3 🥇	51	3	10798	29
	FN funcs	10 🥇	12	11	3538	4943
	Time	0.5s · 3.1s · 0.6s · 3.1s	30s	440s(*)	1.6s	8684s(*)
vyper 780 addresses 21244 functions	FP addrs	0 🥇	30	0	19	0
	FN addrs	0 🥇	780	0	300	780
	FP funcs	0 🥇	30	0	19	0
	FN funcs	0 🥇	21244	0	8273	21244
	Time	9ms · 99ms · 11ms · 42ms	2.0s	34s(*)	26ms	28s(*)

function arguments

Errors - when at least 1 argument is incorrect: (uint256,string) ≠ (uint256,bytes)

Dataset		evmole rs · js · py · go	heimdall
largest1k 24427 functions	Errors	14.0% 🥇 3410	31.1% 7603
	Time	0.6s · 1.3s · 0.7s · 1.8s	370s(*)
random50k 1171102 functions	Errors	4.5% 🥇 52664	19.4% 227077
	Time	16s · 31s · 20s · 48s	8579s(*)
vyper 21244 functions	Errors	46.7% 🥇 9914	100.0% 21244
	Time	0.5s · 1.1s · 0.6s · 1.8s	29s(*)

function state mutability

Errors - Results are not equal (treating view and pure as equivalent to nonpayable)

Errors strict - Results are strictly unequal (nonpayable ≠ view). Some ABIs mark pure/view functions as nonpayable, so not all strict errors indicate real issues.

Dataset		evmole rs · js · py · go	whatsabi	sevm	heimdall
largest1k 24427 functions	Errors	0.0% 🥇 0	68.1% 16623	2.1% 501	25.7% 6268
	Errors strict	18.6% 🥇 4549	79.4% 19393	59.0% 14417	54.8% 13386
	Time	10s · 9.7s · 9.7s · 25s	2.5s	27s(*)	371s(*)
random50k 1160861 functions	Errors	0.0% 🥇 44	30.2% 351060	0.3% 3370	11.5% 133471
	Errors strict	6.8% 🥇 78359	58.2% 675111	55.7% 646831	27.6% 320264
	Time	201s · 184s · 200s · 427s	51s	2261s(*)	8334s(*)
vyper 21166 functions	Errors	0.5% 🥇 110	100.0% 21166	76.3% 16150	100.0% 21166
	Errors strict	4.0% 🥇 850	100.0% 21166	90.2% 19092	100.0% 21166
	Time	11s · 8.7s · 10s · 22s	1.8s	35s(*)	29s(*)

Control Flow Graph

False Negatives - Valid blocks possibly incorrectly marked unreachable by CFG analysis. Lower count usually indicates better precision.

	evmole rs · js · py · go	ethersolve	evm-cfg	sevm	heimdall-rs	evm-cfg-builder
Basic Blocks	97.2% 🥇 663214	93.8% 640383	63.0% 430011	41.4% 282599	31.9% 217924	21.7% 148166
False Negatives	2.8% 🥇 19227	6.2% 42058	37.0% 252430	58.6% 399842	68.1% 464517	78.3% 534275
Time	15s · 20s · 13s · 42s	643s	49s	28s	206s	158s

dataset largest1k, 1000 contracts, 682,441 blocks

notes

See benchmark/README.md for the methodology and commands to reproduce these results

versions: evmole v0.8.3; whatsabi v0.25.0; sevm v0.7.4; evm-hound-rs v0.1.4; heimdall-rs v0.8.6

^(*): sevm and heimdall-rs are full decompilers, not limited to extracting function selectors

How it works

EVMole uses symbolic execution with a custom EVM implementation to trace how CALLDATA flows through the bytecode:

This approach is more accurate than static pattern matching because it follows the actual execution paths the EVM would take, correctly handling complex dispatchers, proxy patterns, and compiler-specific optimizations from both Solidity and Vyper.

Talks

• EVMole: function selectors and arguments from bytecode - BlockSplit 2024
• EVMole: function selectors and arguments from bytecode - EthCC 2024
• Reconstructing Control Flow Graphs from EVM Bytecode - ETHTaipei 2025
• Reconstructing Control Flow Graphs from EVM Bytecode: Faster, Better, Stronger - EthCC 2025

License

MIT