Kalshi KXPRESNOMD 28

{
  "category": null,
  "closes_at": "2026-09-30T23:59:00Z",
  "id": "what-price-will-bitcoin-hit-in-september-2026",
  "markets": [
    {
      "best_ask": 0.08,
      "best_bid": 0.06,
      "liquidity_usd": 45000,
      "outcomes": [
        {
          "name": "Yes",
          "probability": 0.07
        },
        {
          "name": "No",
          "probability": 0.93
        }
      ],
      "question": "Will Bitcoin reach $100,000 in September?",
      "volume_24h_usd": 120000
    }
  ],
  "platform": "polymarket",
  "title": "What price will Bitcoin hit in September?",
  "url": "https://polymarket.com/event/what-price-will-bitcoin-hit-in-september-2026",
  "volume_24h_usd": 891236
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://saylorinnovations.com/api/predictions/kalshi/KXPRESNOMD-28'

# 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://saylorinnovations.com/api/predictions/kalshi/KXPRESNOMD-28' \
  | 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 $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
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 $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fsaylorinnovations.com%2Fapi%2Fpredictions%2Fkalshi%2FKXPRESNOMD-28
const res = await pay("https://saylorinnovations.com/api/predictions/kalshi/KXPRESNOMD-28");
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 $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://saylorinnovations.com/api/predictions/kalshi/KXPRESNOMD-28")
    print(res.status_code, res.text)