signature-lookup

Resolve EVM function selectors (4-byte) and event topic hashes to human-readable signatures. Queries openchain.xyz + 4byte.directory with a built-in fallback DB of 50+ common signatures. Batch mode, bytecode scanning, stdin pipe. Zero dependencies.

Jump to install

Repository: 0xAxiom/axiom-public
Last source activity: June 2, 2026 at 18:06
Detected SKILL.md language: English
Stars: 18
Forks: 2

Install options

The review-first prompt is selected by default. You can switch to a direct command or download a local copy.

Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.

A direct command skips the review prompt. Inspect the source before running it.

npx skills add https://github.com/0xAxiom/axiom-public --skill signature-lookup

The command stays on one line. Scroll horizontally to inspect it before copying.

Prefer a local copy? Download the files currently available to SkillsMP.

Review the source files

Read SKILL.md and any companion files shown by SkillsMP before deciding whether to install.

File Explorer

3 files

SKILL.md

Source instructions · Read-only preview

Back to search Back to installation

signature-lookup

Resolve EVM function selectors and event topic hashes to human-readable signatures. Zero deps.

When to use this skill

You have a 4-byte selector like 0xa9059cbb and want to know it's transfer(address,uint256).

You're reading event logs and need to identify topic0 hashes.

You want to extract all function selectors from deployed bytecode.

You need to quickly identify what a contract can do by scanning its bytecode.

Pairs with calldata-decoder (decode full calldata) and event-decoder (decode full event logs).

What it does NOT require

ethers.js / viem / web3.js

npm install

An API key

A local node

Built-in DB covers 50+ of the most common ERC-20, ERC-721, Uniswap, and access-control signatures, so common lookups work even offline.

Script

lookup.mjs

# Single function selector node lookup.mjs 0xa9059cbb # Event topic hash node lookup.mjs 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef # Batch lookup node lookup.mjs 0xa9059cbb 0x095ea7b3 0x23b872dd # Extract and resolve selectors from bytecode node lookup.mjs --scan 0x6080604052... # Pipe from stdin echo "0xa9059cbb 0x095ea7b3" | node lookup.mjs

Example output

[fn] 0xa9059cbb transfer(address,uint256) [builtin] [fn] 0x095ea7b3 approve(address,uint256) [builtin] [event] 0xddf252ad... Transfer(address,address,uint256) [builtin] 3/3 resolved.

Sources

Built-in DB — instant, no network. Covers ERC-20, ERC-721, Uniswap v2/v3, OpenZeppelin access control, and common DeFi signatures.

openchain.xyz — large public signature database (same one Etherscan uses).

4byte.directory — community-maintained Ethereum signature registry.

Both APIs are queried in parallel; results are deduplicated.

name	signature-lookup
description	Resolve EVM function selectors (4-byte) and event topic hashes to human-readable signatures. Queries openchain.xyz + 4byte.directory with a built-in fallback DB of 50+ common signatures. Batch mode, bytecode scanning, stdin pipe. Zero dependencies.