# Graph Advocate Kalshi-Polymarket Spread Finder

> Graph Advocate Kalshi-Polymarket Spread Finder is a paid API for AI agents from graphadvocate.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Compares Kalshi and Polymarket odds on a given topic to surface arbitrage spreads and directional trade signals between the two prediction markets.

## Facts

- Endpoint: POST https://graphadvocate.com/kalshi-polymarket/spread
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/graph-advocate-kalshi-polymarket-spread-finder-c480b6dc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HdK9rCYdCziG87JNpOzRh

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 graph-advocate-kalshi-polymarket-spread-finder-c480b6dc -d '<json body>'
```

Example prompt: Show me the current spread between Kalshi and Polymarket on 'fed rate cut' — I want to see the basis points, which direction to trade, and which specific tickers are involved.

## When to prefer this

Use this endpoint when you need a direct side-by-side price comparison between Kalshi and Polymarket on the same real-world event and want to identify arbitrage or directional trade opportunities expressed as a spread in basis points. Prefer this over general prediction market APIs when you specifically need cross-platform spread data and actionable trade direction signals.

## Known failure modes

- No matching markets found on one or both platforms for the given topic keyword — returns empty pairs array
- Ambiguous topic keyword matches too many unrelated markets — results may be noisy or mismatched
- Kalshi or Polymarket data temporarily unavailable — stale or partial results
- Rate limit exceeded on free tier (3 queries/day) — requires $0.05 USDC payment via x402 on Base
- Payment not confirmed on Base — request blocked until transaction settles

## How this service works

Cross-source arbitrage spread between Kalshi and Polymarket on a topic. POST {topic, limit?}. Pulls matching markets from both venues (Politics + Elections overlap heavily), computes price mid-spread + arbitrage direction. JOIN that single-source passthrough APIs (incl. Pinax Token API) structurally can't return — this is what survives Pinax shipping Kalshi support later.

## Output

Returns a list of matched market pairs with: spread in basis points, Kalshi yes mid price, Polymarket yes mid price, arbitrage direction (e.g. long-poly-short-kalshi), Kalshi ticker symbol, Polymarket market slug, plus counts of candidate markets found on each platform for the given topic keyword.

## Example request

```json
{
 "topic": "fed rate cut"
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limit": {
   "type": "integer",
   "default": 5,
   "maximum": 10,
   "minimum": 1
  },
  "topic": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "pairs": [
   {
    "spread_bps": 400,
    "kalshi_ticker": "KXFED-25DEC-CUT25",
    "kalshi_yes_mid": 0.62,
    "polymarket_yes_mid": 0.58,
    "arbitrage_direction": "long-poly-short-kalshi",
    "polymarket_market_slug": "fed-rate-cut-december",
    "spread_yes_kalshi_minus_poly": 0.04
   }
  ],
  "topic_keyword": "fed rate",
  "kalshi_candidates": 3,
  "polymarket_candidates": 2
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/graph-advocate-kalshi-polymarket-spread-finder-c480b6dc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from graphadvocate.com](https://www.zero.xyz/host/graphadvocate.com/llms.txt)