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api.x402node.dev crypto selector
https://api.x402node.dev/crypto/selector
payable
Compute the 4-byte function/error selector and full keccak topic from a solidity signature, e.g. transfer(address,uint256). For decoding tx input prefixes and matching event topics. function selector, 4byte, method id, event topic, keccak signature Accepts payment on Base or Solana — either network works.
We sent a real
GET request to this endpoint and it
answered 402 with payment requirements we could parse.
- Price
- $0.01
- Network
- base
- Pay to
- 0x4466d4A84b7c49a6A094ec6eef4a0712D6dd125e
- Spec dialect
- v2 (declares x402Version 2)
- Transport
- PAYMENT-REQUIRED header
- HTTP method
- GET
- Response latency
- 47 ms
- Payment options
- 2 usable of 2
- Last checked
- 2026-08-10T09:18:19.309Z (1d ago)
- Category
- finance-crypto
Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fapi.x402node.dev%2Fcrypto%2Fselector"