# Polymarket vs Kalshi Yes-Price Spread Lookup

> Polymarket vs Kalshi Yes-Price Spread Lookup is a paid API for AI agents from aizamon.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-20).

Returns the yes-price spread between Polymarket and Kalshi for a given prediction market topic, identifying the cheaper venue and providing deep links.

## Facts

- Endpoint: GET https://aizamon.com/x402/v1/spread?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polymarket-vs-kalshi-yes-price-spread-lookup-66255f49
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_uTc7sgA4HnBsCozsp0Bx6

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 polymarket-vs-kalshi-yes-price-spread-lookup-66255f49
```

Example prompt: What's the yes-price spread between Polymarket and Kalshi for the 2024 US election winner market — which venue is cheaper and by how much?

## When to prefer this

Choose this endpoint when you need a quick, cheap ($0.01) single-market yes-price comparison between Polymarket and Kalshi, especially for spot-checking a specific topic or finding the top gap opportunity without paying for a bulk arbitrage pack. Prefer the $0.89 pack endpoint if you need the top 5 gaps with fee-adjusted net edge data instead.

## Known failure modes

- No matching market found for the given topic query — returns empty or null result
- Topic query too ambiguous to resolve to a unique market on both venues
- One or both venues may not have a listed market for the query, resulting in partial data
- Network or upstream API errors from Polymarket or Kalshi data sources
- Payment failure or x402 authorization issue preventing the call from completing

## How this service works

Exact Polymarket and Kalshi yes prices for one topic. Pass ?q= as keywords, or omit q for the widest live gap. Returns gapCents, the cheaper venue, the Kalshi ticker and URL, and the Polymarket slug and URL. This is the mid-price gap. The cents left after you buy the ask and sell the bid are the net read. $0.001 USDC. The hour pass covers it.

## Output

Returns the exact yes prices on both Polymarket and Kalshi, the gap in cents between them, which venue is cheaper, and direct deep links to both market pages — all in a single composable read.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "q": {
       "type": "string",
       "description": "Market topic keywords. Omit for the top live gap."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "sku": {
       "type": "string"
      },
      "result": {
       "type": "object"
      },
      "protocol": {
       "type": "string"
      }
     },
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "sku": "SKU_AG_SPREAD_01",
  "result": {
   "spread": {
    "query": "openai ipo",
    "topic": "Will Anthropic or OpenAI IPO first?",
    "kalshi": {
     "url": "https://kalshi.com/…",
     "yes": 0.42,
     "ticker": "…"
    },
    "gapCents": 8,
    "cheaperOn": "kalshi",
    "polymarket": {
     "url": "https://polymarket.com/…",
     "yes": 0.5,
     "slug": "…"
    }
   },
   "product": "Cross-venue Spread — exact tick"
  },
  "protocol": "x402"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polymarket-vs-kalshi-yes-price-spread-lookup-66255f49/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from aizamon.com](https://www.zero.xyz/host/aizamon.com/llms.txt)