B20 payment memos

Payment memos attached to B20 transfers: pairs each Memo(address,bytes32) log with its Transfer at the previous log index (same tx, same token). Give a tx hash for one transaction, or scan a block window. Returns memoHex always and memoText when printable UTF-8. ?token=0xb200…&tx=0x…|&blocks=50000&address=0x…&limit=50

Input

Example output

{
  "token": "0xb200…0001",
  "mode": "window",
  "fromBlock": 1,
  "toBlock": 2,
  "scannedFromBlock": 1,
  "truncated": false,
  "count": 0,
  "memos": []
}

Try it — see the 402 challenge (free)

curl -i "https://agent402.tools/api/b20-memos?token=0xb200000000000000000000000000000000000001&blocks=1000"

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/b20-memos?token=0xb200000000000000000000000000000000000001&blocks=1000");

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