# polynews.news Polymarket-Kalshi Arbitrage Detection

> polynews.news Polymarket-Kalshi Arbitrage Detection is a paid API for AI agents from polynews.news, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Detects cross-platform arbitrage opportunities between Polymarket and Kalshi by matching markets, computing price spreads, and calculating fee-adjusted expected value

## Facts

- Endpoint: GET https://polynews.news/api/v1/arbitrage
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polynews-news-ce99ce41
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zhDqo-YWGGa4RcCc1QgMe

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 polynews-news-ce99ce41
```

Example prompt: Show me the top 10 arbitrage opportunities right now between Polymarket and Kalshi — I want to see matched markets, the price spreads, and the fee-adjusted expected value for each.

## When to prefer this

Use this endpoint when you need real-time, fee-adjusted arbitrage signals specifically between Polymarket and Kalshi. Prefer it over manually querying each platform's API separately, or when you need pre-matched market pairs with EV already calculated rather than raw price feeds.

## Known failure modes

- No matched markets found if category filter is too narrow
- Empty opportunities array if no price divergence currently exists
- Rate limiting or payment failure for the $0.01 USDC per-call fee
- Invalid category parameter returns empty or error response
- Stale data if market prices were recently updated on either platform

## How this service works

Cross-platform arbitrage detection between Polymarket and Kalshi: matched markets, price spreads, fee-adjusted EV. Coverage: liquid Polymarket markets in politics/geopolitics/elections/tech/economy/finance; low-volume long-tail, sports, culture, and weather are not included.

## Output

Returns a list of arbitrage opportunities with matched market pairs, raw price spreads between Polymarket and Kalshi, fee-adjusted expected value (EV) for each opportunity, the Polymarket question text, and the Kalshi market title. Also includes a count of total matched markets found.

## Example request

```json
{
 "input": {
  "type": "http",
  "method": "GET",
  "queryParams": {
   "limit": "10",
   "category": "politics"
  }
 }
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "limit": {
       "type": "string"
      },
      "category": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "data": {
       "type": "object",
       "properties": {
        "opportunities": {
         "type": "array",
         "items": {
          "type": "object",
          "properties": {
           "arbitrage": {
            "type": "object",
            "properties": {
             "type": {
              "type": "string",
              "description": "e.g. BUY_YES_POLY_NO_KALSHI"
             },
             "spreadNet": {
              "type": "number",
              "description": "After fees"
             },
             "spreadRaw": {
              "type": "number"
             },
             "confidence": {
              "type": "string",
              "description": "high | medium | low"
             },
             "impliedProfit": {
              "type": "number",
              "description": "Fee-adjusted EV"
             }
            },
            "description": "Fee-adjusted arb calc"
           },
           "kalshiTitle": {
            "type": "string"
           },
           "kalshiYesAsk": {
            "type": "number"
           },
           "matchConfidence": {
            "type": "number"
           },
           "polymarketQuestion": {
            "type": "string"
           },
           "polymarketYesPrice": {
            "type": "number"
           }
          }
         }
        },
        "matchedMarkets": {
         "type": "number"
        }
       }
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "computedAt": "2026-05-12T04:25:00.000Z",
   "opportunities": [
    {
     "spreadRaw": 0.09,
     "kalshiPrice": 0.41,
     "kalshiTitle": "BTC at or above $200,000 by Dec 31, 2026",
     "expectedValue": 0.052,
     "matchConfidence": 0.87,
     "polymarketPrice": 0.32,
     "recommendedSide": "BUY polymarket / SELL kalshi",
     "polymarketQuestion": "Will Bitcoin reach $200K by Dec 31, 2026?"
    }
   ],
   "matchedMarkets": 73,
   "kalshiDataAgeSec": 45,
   "totalPolymarkets": 1074,
   "totalKalshiMarkets": 13802,
   "polymarketDataAgeSec": 30
  },
  "meta": {
   "tier": "alpha",
   "version": "v1",
   "endpoint": "/api/v1/arbitrage",
   "latencyMs": 1240,
   "timestamp": "2026-05-12T04:30:00.000Z"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polynews-news-ce99ce41/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from polynews.news](https://www.zero.xyz/host/polynews.news/llms.txt)