Appraise

Call it

GET https://www.retcg.xyz/api/appraise/pokemon:swsh7-215
→ 402 Payment Required · PAYMENT-REQUIRED: base64 { accepts: [Arc, Base, Polygon, Solana] }
→ pay $0.02 in USDC from whichever chain you hold it on, repeat the request
→ 200 · rows, set, projections, pnl, breakeven, attest

The id is a pokemontcg.io card id (sv3pt5-199 is 151 Charizard ex). Any x402 client pays it; with @x402/fetch it is one wrapped fetch:

import { wrapFetchWithPaymentFromConfig } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const pay = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(privateKeyToAccount(KEY)) }],
});
const r = await pay("https://www.retcg.xyz/api/appraise/pokemon:swsh7-215?denoms=USD,EUR,SOL");
const { rows, set, projections, pnl, attest } = await r.json();

Solana pays with @x402/svm; Arc pays from a Circle Gateway balance with @circle-fin/x402-batching. The unpaid 402 already carries the set, its momentum and the raw levels, free — and /api/appraise/sets is every set's phase, momentum and heat, free.

What comes back

A real answer, paid for on 20 September 2026 — Umbreon VMAX, Evolving Skies 215/203:

cond      USD        EUR        SOL     basis
raw       1,928.88   1,289.51   17.59   observed · ebay sold · n 5 · 15→19 Sep
PSA 10    4,500.00   3,918.99   41.05   observed · ebay sold · n 5 · 15→20 Sep
BGS 9.5   2,575.00   2,242.53   23.49   observed · ebay sold · n 2 · 19 Sep

set       Evolving Skies · out of print · 1,850 days · shelved by Fusion Strike
          momentum −1.4% / 30 d · heat 0.37 · drift (out of print) −0.38% / 30 d, n 58
raw@365   1,841.76  → eBay net 1,596.18 (−17.2%)   raw → PSA 10: +$80 grading → net 3,645.88 (+89.0%)
attest    EIP-712 · signer 0xb0Fd9c696CE8B93Aee2e9f63A43A28383A5fa947

• rows — every condition (raw, PSA 1–10, BGS/CGC/SGC with halves) in USD, EUR, USDC, EURC, GBP, JPY, ETH, SOL, BTC. USD and EUR are their own markets (eBay sold, TCGplayer, Cardmarket); the rest are converted and say so. A condition nobody has sold is priced from the set's grade ladder, marked ladder, or left null. No basis, no number.
• set — the phase from the release calendar (launch, in print, shelved, out of print, vintage), 30-day momentum against every other set, heat.
• drift · projections — what sets in each phase did last month, measured across 174 sets nightly, and the level compounded through the phases ahead at 30/90/180/365 days. An unmeasured phase on the path voids the projection rather than filling it.
• pnl · breakeven — what a sale nets after eBay, TCGplayer, Mercari or Cardmarket fees and postage, including raw → graded with the grading fee; break-even at the fee then ($25) and now ($80). ?paid= and ?on= make it your purchase.
• attest — an EIP-712 signature over the rows, so any chain can verify a figure with one ecrecover.

For agents and directories

• OpenAPI 3.1 with x-payment-info: /api/appraise/openapi.json
• x402 manifest: /.well-known/x402 (and the _x402.retcg.xyz TXT record)
• In words: /llms.txt
• Route template /api/appraise/:id · scheme exact · asset USDC · networks eip155:5042 · eip155:8453 · eip155:137 · solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp

Pokémon only for now. Vintage keywords can pool editions (a Base Set Charizard's raw pile mixes Unlimited with Shadowless); the answer flags the disagreement rather than hiding it. Questions: contact@retcg.xyz or the Discord.