# Cross-Platform Prediction Market Arbitrage Scanner (Polymarket vs Kalshi)

> Cross-Platform Prediction Market Arbitrage Scanner (Polymarket vs Kalshi) is a paid API for AI agents from oracle.the-undesirables.com, paid per call via x402, $1/call, status unknown (last checked 2026-09-15).

Scans for price discrepancies between Polymarket and Kalshi prediction markets using Gen3 NLI to identify cross-platform arbitrage opportunities.

## Facts

- Endpoint: GET https://oracle.the-undesirables.com/api/v1/arb-cross
- Price: $1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/oracle-the-undesirables-com-b670f476
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vephMzmKLRA1onMwX8J-P

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability oracle-the-undesirables-com-b670f476
```

Example prompt: Scan for cross-platform arbitrage opportunities between Polymarket and Kalshi right now — I want to see any events where the prices diverge enough to lock in a profit.

## When to prefer this

Use this endpoint when you need to identify exploitable price gaps between Polymarket and Kalshi specifically, leveraging NLI-based semantic event matching to align contracts across the two platforms. Prefer over single-platform scanning tools when cross-platform arbitrage is the goal.

## Known failure modes

- No matching events found across platforms — returns empty result set
- Rate limit or API unavailability on Polymarket or Kalshi data feeds — returns 503 or partial data
- Gen3 NLI semantic matching fails to align events — may produce false positives or mismatched pairs
- Payment not processed via x402 — returns 402 Payment Required
- Network latency causes stale price data — spread may be inaccurate by the time agent acts

## How this service works

TCG card grading, conformal risk forecasting, and market intelligence. Powered by x402 micropayments — USDC on Base, USDC on Solana, or USDG on Robinhood Chain; the 402 offers all three and the agent picks a leg. Free tools require no payment. Paid tools return HTTP 402 — sign a payment and retry with the payment proof header.

## Output

A list of matched prediction market events across Polymarket and Kalshi with their respective prices, the spread between them, and the implied arbitrage profit opportunity. Powered by Gen3 NLI for semantic event matching across platforms.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": "ok",
  "scan_type": "cross-platform",
  "opportunities": [
   {
    "market1": "Kalshi",
    "market2": "Polymarket",
    "edge_percent": 6.8
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/oracle-the-undesirables-com-b670f476/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from oracle.the-undesirables.com](https://www.zero.xyz/host/oracle.the-undesirables.com/llms.txt)