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pastable-x402 EVM Keccak256 Hash
x402
pastable-x402 EVM Keccak256 Hash is a paid API for AI agents from pastable-x402.pages.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).
Computes the Keccak-256 hash of a string input (UTF-8 or hex encoded), returning both the full hash and 4-byte function selector
Price / call$0.02
Success—
StatusUnknown
How this service works
Pay-per-call utility APIs for agents: EVM helpers (checksum, unit conversion, keccak), data transforms (CSV to JSON, JSON diff, URL canonicalisation), text tools (hashing, JWT decode), and Bazaar market intelligence. x402 on Base mainnet.
Output
Returns a JSON object containing the original input string, the encoding used (utf8 or hex), the full 32-byte keccak256 hash as a 0x-prefixed hex string, and the first 4 bytes as the EVM function selector (e.g. {"input":"hello","encoding":"utf8","selector":"0x1c8aff95","keccak256":"0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"}).
Example use cases
Derive Solidity function selector
“What's the 4-byte function selector for 'balanceOf(address)'? Hash it with keccak256 using utf8 encoding.”
Hash hex-encoded smart contract data
“I have some hex-encoded data '48656c6c6f' — can you keccak256-hash it using hex encoding for use in an Ethereum transaction?”
Verify event topic hash
“Compute the keccak256 of 'Transfer(address,address,uint256)' in utf8 — I need to confirm it matches the ERC-20 Transfer event topic.”
Technical details
Endpoint
GEThttps://pastable-x402.pages.dev/evm/keccakWhen to prefer
Choose this endpoint when you need a quick, pay-per-call keccak256 hash without setting up a local library — especially useful for AI agents deriving EVM function selectors or event topic hashes on the fly. Prefer it over local computation when you need a trusted, externally-verifiable result in an agent pipeline that already handles x402 micropayments on Base.
Side effects
- Missing required 'data' query parameter returns an error
- Invalid encoding value (not 'utf8' or 'hex') may return a 400 or unexpected result
- Malformed hex string when encoding=hex may fail to hash correctly
- Payment failure on Base mainnet (insufficient USDC) returns HTTP 402
- Network or Cloudflare Pages outage returns 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"input": "hello",
"encoding": "utf8",
"selector": "0x1c8aff95",
"keccak256": "0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
}
}Tags
x402
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