# Polymarket & Kalshi Odds

> Polymarket & Kalshi Odds is a paid API for AI agents from agent-data.centorprat.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Fetches real-time prediction market odds from Polymarket and Kalshi, including implied probabilities, bid/ask spreads, volume, liquidity, and cross-venue probability spreads for matched questions.

## Facts

- Endpoint: POST https://agent-data.centorprat.workers.dev/tools/polymarket-kalshi-odds?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polymarket-kalshi-odds-58c1209f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_utUq9GtCPTw4tfH7Zt5D7

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-kalshi-odds-58c1209f -d '<json body>'
```

Example prompt: What are the current implied probabilities for a Fed rate cut on both Polymarket and Kalshi — and show me the spread between the two venues if they list the same question?

## When to prefer this

Use this endpoint when you need real-time prediction market data from both Polymarket and Kalshi in a single call, especially for cross-venue probability comparisons or arbitrage detection. Prefer it over manually querying each platform's API when you want normalized implied probabilities and spread data without an API key.

## Known failure modes

- No markets found for a query — returns empty result set (not charged)
- Query too broad — may return up to maxMarketsPerQuery results per venue with no further filtering
- Venue-specific outage — one venue may return data while the other fails
- Cross-venue match finds no paired questions — returns unpaired results only
- minVolume24hUsd too high — filters out all markets and returns empty list

## How this service works

Pay-per-call data and tools for AI agents, $0.002-0.01 per call in USDC via x402 (Base, Polygon or Solana), no account or API key; MAX tiers ($0.05-0.25) run deeper jobs. Agent toolkit: web search, search + read top pages, any page as clean markdown with a prompt-injection check, which-x402-API-to-call recommender, seller check. Data: Google Maps places with contacts, YouTube video data and transcripts, job listings (Indeed, LinkedIn, 13 boards), Google Ads Transparency, TikTok comments, Pinterest, Airbnb, Redfin, AliExpress, app stores, live sports, website and SEO checks, Shopify store tech stacks, and onchain token / address risk checks.

## Output

Returns a list of prediction market contracts per venue with: market question, implied probability, bid/ask, 24h and 7d price moves, 24h volume in USD, liquidity/open interest, and close time. When cross-venue matching is enabled, also returns paired markets from both Polymarket and Kalshi with the probability spread between them.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "sortBy": {
   "enum": [
    "volume24hr",
    "liquidity",
    "endDate"
   ],
   "type": "string",
   "description": "Order of the most-active list."
  },
  "venues": {
   "type": "array",
   "items": {
    "enum": [
     "polymarket",
     "kalshi"
    ],
    "type": "string"
   },
   "maxItems": 3,
   "description": "Which prediction markets to read (default both)."
  },
  "queries": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 1,
   "description": "What to search, e.g. [\"fed rate\", \"bitcoin\", \"election\"]. Leave empty for the most active markets."
  },
  "minVolume24hUsd": {
   "type": "integer",
   "description": "Skip thinly traded markets."
  },
  "crossVenueMatches": {
   "type": "boolean",
   "description": "Pair the same question on Polymarket and Kalshi and report the probability spread (free rows)."
  },
  "maxMarketsPerQuery": {
   "type": "integer",
   "maximum": 25,
   "description": "Up to this many markets per venue for each topic."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "items": [
   {
    "url": "https://polymarket.com/event/bitcoin-above-on-october-23-2026",
    "venue": "polymarket",
    "bestAsk": 1,
    "bestBid": 0.999,
    "change7d": null,
    "closesAt": "2026-10-23T16:00:00Z",
    "outcomes": [
     {
      "outcome": "Yes",
      "probability": 0.9995
     },
     {
      "outcome": "No",
      "probability": 0.0005
     }
    ],
    "question": "Will the price of Bitcoin be above $72,000 on October 23?",
    "change24h": 0.001,
    "volumeUsd": 34250.394056,
    "eventTitle": "Bitcoin above ___ on October 23?",
    "liquidityUsd": 122378.67304,
    "volume24hUsd": 27635.37,
    "yesProbability": 0.9995
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polymarket-kalshi-odds-58c1209f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-data.centorprat.workers.dev](https://www.zero.xyz/host/agent-data.centorprat.workers.dev/llms.txt)