Pay NEXUS in 60 seconds

Cross-venue Kalshi ↔ Polymarket spread via x402 on Base. $0.02 USDC per call.

Fed spread live: 22.75pt

Kalshi 47.0% · Polymarket 69.75% · kalshi_yes_cheaper

First stranger paid call: reaworks-x402-paid-readback/1.0 — $0.02 USDC · leaderboard

Live 402 invoice (right now)

{
  "x402Version": 2,
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "amount": "20000",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "payTo": "0xc91cE6291eDC0713ec753BAFBA002506ffb2b95c",
      "maxTimeoutSeconds": 300,
      "facilitator": "https://x402.org/facilitator",
      "paymentContextToken": "",
      "extra": {
        "name": "USDC",
        "version": "2"
      },
      "resource": "https://nexus-agent-xa12.onrender.com/arb/check?markets=Fed,BTC",
      "description": "Kalshi vs Polymarket spread \u2014 cross-venue arb for trading bots"
    }
  ],
  "network": "eip155:8453",
  "amount_usdc": 0.02
}

Step 0 — Test free endpoint first

curl 'https://nexus-agent-xa12.onrender.com/kalshi?market=Fed'
curl 'https://nexus-agent-xa12.onrender.com/probe'

No wallet needed. Confirms data is live before you pay.

Step 1 — awal CLI (fastest for cron / humans)

npm install -g @x402/cli
awal wallet create
awal wallet fund
awal x402 pay 'https://nexus-agent-xa12.onrender.com/arb/check?markets=Fed,BTC'

Send X-NEXUS-Source: your-bot-name on repeat calls for trace credit.

Step 2 — @x402/fetch (Node agents)

npm install @x402/fetch
import { wrapFetchWithPayment } from '@x402/fetch';

const fetchWithPay = wrapFetchWithPayment(fetch, { privateKey: process.env.PRIVATE_KEY });
const res = await fetchWithPay('https://nexus-agent-xa12.onrender.com/arb/check?markets=Fed,BTC');
console.log(await res.json());

Step 3 — curl + X-Payment (existing Base key)

export PRIVATE_KEY=0xYOUR_KEY
# Sign x402 v2 exact payload for eip155:8453, then:
curl -H 'X-Payment: YOUR_SIGNED_PAYMENT_HEADER' \
  'https://nexus-agent-xa12.onrender.com/arb/check?markets=Fed,BTC'

Prefer awal unless you already have a signing pipeline. MCP equivalent: POST https://nexus-agent-xa12.onrender.com/mcp tool check_kalshi_polymarket_arb.

What you get back ($0.02 → 200 JSON)

{
  "markets": [
    "Fed"
  ],
  "comparisons": [
    {
      "market": "Fed",
      "kalshi_price": 42.0,
      "polymarket_price": 69.55,
      "spread": 27.55,
      "direction": "kalshi_yes_cheaper"
    }
  ]
}

Verify your receipt

curl 'https://nexus-agent-xa12.onrender.com/revenue/verify?tx=YOUR_TX_HASH'
curl 'https://nexus-agent-xa12.onrender.com/trace/bots?limit=10'
curl 'https://nexus-agent-xa12.onrender.com/receipt?action_type=arb.check&scope=Fed,BTC'

Leaderboard · Wallet compat test · AgentKit tool

Raw quantitative data for research and model verification only. Not financial advice.