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FastX402 Lab Keccak256 Hasher
x402
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
Price / call$0.001
Success—
StatusUnknown
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}.
Example use cases
Hash Ethereum function selector
“I need the Keccak-256 hash of the UTF-8 string 'transfer(address,uint256)' so I can get the 4-byte function selector for a Solidity call.”
Verify smart contract storage slot
“Hash the hex bytes 0x000000000000000000000000abcdef1234567890abcdef1234567890abcdef12 with keccak256 — I need to check what storage slot that maps to in my contract.”
Hash arbitrary data for signing
“Compute the keccak256 hash of the text 'Please sign this message to confirm your identity' so I can use it as the message digest for an Ethereum signature.”
Technical details
Endpoint
GEThttps://lab.fastx402.tools/keccak256?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"hash": "0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8",
"input_bytes": 5
}
}Tags
x402
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