Fen Board

{
  "asOf": "2026-10-12T01:02:03.062Z",
  "ascii": "8 r . b q k b n r\n7 p p p p . p p p\n6 . . n . . . . .\n5 . . . . p . . .\n4 . . . . P . . .\n3 . . . . . N . .\n2 P P P P . P P P\n1 R N B Q K B . R\n  a b c d e f g h",
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "notChecked": [
    "position legality (use /fen-parse)",
    "whose move or any rights beyond the placement"
  ],
  "pieceCount": 32,
  "pieces": [
    {
      "color": "white",
      "piece": "rook",
      "square": "a1"
    },
    {
      "color": "white",
      "piece": "knight",
      "square": "b1"
    }
  ],
  "reasons": [],
  "rows": [
    "8 r . b q k b n r",
    "7 p p p p . p p p",
    "…7 more"
  ],
  "source": "computed locally (FEN piece placement)",
  "summary": "32 piece(s) on the board.",
  "verdict": "RENDERED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://chess-notation.x402tookit.com/fen-board?fen=r1bqkbnr%2Fpppp1ppp%2F2n5%2F4p3%2F4P3%2F5N2%2FPPPP1PPP%2FRNBQKB1R+w+KQkq+-+2+3'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://chess-notation.x402tookit.com/fen-board?fen=r1bqkbnr%2Fpppp1ppp%2F2n5%2F4p3%2F4P3%2F5N2%2FPPPP1PPP%2FRNBQKB1R+w+KQkq+-+2+3' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

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

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fchess-notation.x402tookit.com%2Ffen-board
const res = await pay("https://chess-notation.x402tookit.com/fen-board?fen=r1bqkbnr%2Fpppp1ppp%2F2n5%2F4p3%2F4P3%2F5N2%2FPPPP1PPP%2FRNBQKB1R+w+KQkq+-+2+3");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://chess-notation.x402tookit.com/fen-board?fen=r1bqkbnr%2Fpppp1ppp%2F2n5%2F4p3%2F4P3%2F5N2%2FPPPP1PPP%2FRNBQKB1R+w+KQkq+-+2+3")
    print(res.status_code, res.text)