# Ethereum Keccak256 Hash (Original Keccak, not NIST SHA3)

> Ethereum Keccak256 Hash (Original Keccak, not NIST SHA3) is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Computes the Ethereum-native Keccak256 hash (the original Keccak algorithm, not NIST SHA3) of a hex-encoded byte sequence or plain text string

## Facts

- Endpoint: POST https://twin.unykorn.org/hash-keccak256?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ethereum-keccak256-hash-original-keccak-not-nist-sha3-bdfb4dab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_W49V8t9lVc29FdfpMoCc3

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability ethereum-keccak256-hash-original-keccak-not-nist-sha3-bdfb4dab -d '<json body>'
```

Example prompt: Compute the Keccak256 hash (Ethereum-style, not NIST SHA3) of the text 'Transfer(address,address,uint256)' so I can get the ABI event topic signature.

## When to prefer this

Choose this endpoint when you specifically need the original Ethereum Keccak256 algorithm (as used by Solidity, Web3, and EVM tooling) rather than the NIST-standardized SHA3-256, which produces different output for the same input. It is ideal for computing ERC-20/ERC-721 event topic hashes, Solidity function selectors, ENS label hashes, or any other on-chain hash that must match EVM behavior. Prefer this over general-purpose SHA3 libraries or endpoints when correctness against Ethereum's non-NIST variant matters.

## Known failure modes

- Invalid hex input (not matching ^0x[0-9a-fA-F]*$ pattern) returns validation error
- Text input exceeding 49152 characters rejected
- Missing both hex and text parameters returns error
- Payment failure via x402 protocol blocks execution
- Malformed JSON body returns parse error

## How this service works

Ethereum keccak256 — the original Keccak, not NIST SHA3 — Genesis402 / UnyKorn Operator Network

## Output

Returns a JSON object with ok=true, the type field set to 'hash-keccak256', the computed Keccak256 digest, a payment receipt including transaction hash, USD amount, and a unique receipt ID, and an ISO8601 timestamp of when the hash was generated.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "hex": {
     "type": "string",
     "pattern": "^0x[0-9a-fA-F]*$"
    },
    "text": {
     "type": "string",
     "maxLength": 49152
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "hash-keccak256",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.001,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ethereum-keccak256-hash-original-keccak-not-nist-sha3-bdfb4dab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)