# Kalshi vs Polymarket Sports Odds Cross-Venue API

> Kalshi vs Polymarket Sports Odds Cross-Venue API is a paid API for AI agents from golf-evm-math.x402-evm-math.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-28).

Returns cross-venue US sports game-winner odds from Kalshi and Polymarket with taker fees and edge-after-fees calculations, updated every 5 minutes.

## Facts

- Endpoint: GET https://golf-evm-math.x402-evm-math.workers.dev/data/sports-xvenue?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/kalshi-vs-polymarket-sports-odds-cross-venue-api-0a5bdb0f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ua_b9XC-haVbgTQyEF081

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 kalshi-vs-polymarket-sports-odds-cross-venue-api-0a5bdb0f
```

Example prompt: Pull the latest cross-venue odds for US sports games comparing Kalshi and Polymarket prices, and show me which matchups have the best edge after taker fees right now.

## When to prefer this

Choose this endpoint when you need a single aggregated view of game-winner prices across both Kalshi and Polymarket with fees already factored in, rather than querying each venue separately and manually computing net edge. Ideal for arbitrage bots, trading agents, or anyone comparing prediction market odds in real time without building their own cross-venue fee model.

## Known failure modes

- Stale data if upstream Kalshi or Polymarket APIs are delayed beyond 5-minute refresh window
- Empty games array if no active markets are currently listed
- Payment failure if USDC micropayment via x402 is not properly configured
- HTTP 402 if payment header is missing or insufficient
- Negative edge on all games meaning no arbitrage opportunity currently exists

## How this service works

Exact EVM address, calldata, Uniswap V2/V3 and impermanent-loss math. Pay per call in USDC on Base via x402.

## Output

A JSON object containing a list of games, each with league, team matchup, Polymarket bid price, Kalshi yes ask price, the best cross-venue combo strategy, total all-in cost, and edge after fees. Also includes data age in seconds to indicate how fresh the feed is.

## 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": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "games": [
   {
    "league": "nfl",
    "pm_bid": 0.57,
    "team_a": "SF",
    "team_b": "ATL",
    "best_combo": "pm_long_SF+kalshi_no",
    "all_in_cost": 1.0319,
    "kalshi_yes_ask": 0.58,
    "edge_after_fees": -0.0319
   }
  ],
  "age_seconds": 120
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/kalshi-vs-polymarket-sports-odds-cross-venue-api-0a5bdb0f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from golf-evm-math.x402-evm-math.workers.dev](https://www.zero.xyz/host/golf-evm-math.x402-evm-math.workers.dev/llms.txt)