# FastX402 Lab Keccak256 Hasher

> FastX402 Lab Keccak256 Hasher is a paid API for AI agents from lab.fastx402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-17).

Computes the Keccak-256 hash of a given hex byte string or UTF-8 text, paid per call in USDC over x402

## Facts

- Endpoint: GET https://lab.fastx402.tools/keccak256?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastx402-lab-keccak256-hasher-a20bc6a3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SWda7EfhQ-zIKFa4R2QS3

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 fastx402-lab-keccak256-hasher-a20bc6a3
```

Example prompt: Can you compute the Keccak-256 hash of the UTF-8 text 'hello world'?

## When to prefer this

Choose this endpoint when you need a quick, no-signup Keccak-256 hash computation (for Ethereum/EVM use cases) and can pay $0.001 USDC per call via x402. Prefer it over running a local library when your agent environment lacks crypto libraries, or when you want a simple pay-as-you-go API with no key management. Not suitable if you need SHA-256 or other hash functions, or if you require batch hashing of many inputs cost-effectively.

## Known failure modes

- Missing both 'hex' and 'text' query params — endpoint may return an error or hash empty input
- Invalid hex string format (e.g. odd-length or non-hex chars) — returns error
- Payment failure or insufficient USDC balance — returns HTTP 402 and no hash
- Network timeout on the Base chain payment — request fails before hashing occurs

## How this service works

FastX402 Lab: small pay-per-call tools for AI agents, paid per request in USDC on Base over x402. No signup, no API key.

## Output

Returns a JSON object with 'hash' (the 0x-prefixed 32-byte Keccak-256 digest as a hex string) and 'input_bytes' (the number of bytes that were hashed). Example: {"hash":"0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8","input_bytes":5}.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "hex": {
       "type": "string",
       "description": "Hex bytes to hash, like 0x68656c6c6f; \"0x\" is empty"
      },
      "text": {
       "type": "string",
       "description": "UTF-8 text to hash"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "hash": {
       "type": "string"
      },
      "input_bytes": {
       "type": "integer"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hash": "0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8",
  "input_bytes": 5
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastx402-lab-keccak256-hasher-a20bc6a3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from lab.fastx402.tools](https://www.zero.xyz/host/lab.fastx402.tools/llms.txt)