Node.js Keccak-256

Ethereum uses Keccak-256, not the NIST-standardized SHA3 variant exposed by Node's crypto.createHash('sha3-256').

Scope: Ethereum hashing only — function selectors, event topics, EIP-712, Merkle proofs, storage slots, address derivation.

MUST NOT: Rewrite Node createHash('sha256') used for JWT tokens, OAuth PKCE, API keys, or other app secrets. Keccak is not SHA-256.

Prefer: keccak256 from viem when viem is already a project dependency. Use ethers only when the app already depends on it.

When to Use

• Computing Ethereum function selectors or event topics
• Building EIP-712, signature, Merkle, or storage-slot helpers in JS/TS
• Reviewing any code that hashes Ethereum data with Node crypto directly

How It Works

The two algorithms produce different outputs for the same input, and Node will not warn you.