Appraise

{
  "attest": {
    "root": "0x…",
    "signature": "0x…",
    "signer": "0xb0Fd9c696CE8B93Aee2e9f63A43A28383A5fa947"
  },
  "card": {
    "name": "Charizard ex",
    "number": "199",
    "rarity": "Special illustration rare"
  },
  "id": "pokemon:sv3pt5-199",
  "paid": true,
  "projections": {
    "raw@365": {
      "steps": [
        {
          "days": 365,
          "drift30": -0.0038,
          "n": 58,
          "phase": "out-of-print"
        }
      ],
      "value": 300.77
    }
  },
  "rows": [
    {
      "basis": {
        "from": "2026-02-27",
        "kind": "observed",
        "n": 2,
        "src": "ebay sold",
        "to": "2026-09-19"
      },
      "cond": "PSA 9",
      "denom": "USD",
      "expo": -8,
      "mant": 37160000000,
      "price": 371.6
    }
  ],
  "set": {
    "ageDays": 1094,
    "heat": 0.69,
    "momentum30": 0.042,
    "name": "151",
    "phase": "out-of-print"
  }
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://www.retcg.xyz/api/appraise/:id?denoms=USD%2CEUR%2CSOL&on=2026-06-01&paid=12.50'

# 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://www.retcg.xyz/api/appraise/:id?denoms=USD%2CEUR%2CSOL&on=2026-06-01&paid=12.50' \
  | 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%2Fwww.retcg.xyz%2Fapi%2Fappraise%2F%3Aid
const res = await pay("https://www.retcg.xyz/api/appraise/:id?denoms=USD%2CEUR%2CSOL&on=2026-06-01&paid=12.50");
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://www.retcg.xyz/api/appraise/:id?denoms=USD%2CEUR%2CSOL&on=2026-06-01&paid=12.50")
    print(res.status_code, res.text)