# Prediction Markets Aggregator (Polymarket + Kalshi)

> Prediction Markets Aggregator (Polymarket + Kalshi) is a paid API for AI agents from api.x-402.online, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-01).

Fetches open prediction markets from Polymarket and Kalshi in a single call, returning question, outcome probabilities, 24h volume, liquidity, closing time, and link, sorted by volume with optional keyword filtering.

## Facts

- Endpoint: GET https://api.x-402.online/v1/markets/prediction?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/prediction-markets-aggregator-polymarket-kalshi-65fca0cc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_YwYYakSFvv-QSKaKoqwXG

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 prediction-markets-aggregator-polymarket-kalshi-65fca0cc
```

Example prompt: Find me the top 10 open prediction markets about the US election from both Polymarket and Kalshi — I want to see the current probabilities, 24h volume, and links.

## When to prefer this

Use this endpoint when you need a unified, real-time view of open prediction markets across both Polymarket and Kalshi in a single call, especially when you want to compare odds, liquidity, and volume across platforms without maintaining integrations with each separately. Ideal for agents doing political or financial sentiment analysis, research on crowd-sourced probabilities, or monitoring which topics have the most active speculative markets.

## Known failure modes

- No markets match the keyword filter — returns empty list
- Upstream Polymarket or Kalshi API unavailable — partial or failed response
- Invalid source parameter — returns error
- Rate limit or payment failure — 402 payment required response

## How this service works

Open prediction markets from Polymarket and Kalshi in one call: question, outcome probabilities, 24 h volume, liquidity, closing time and link, sorted by volume, with an optional keyword filter. Query: ?q=election&limit=10&sources=polymarket,kalshi

## Output

A ranked list of open prediction markets (sorted by 24h volume) from Polymarket and/or Kalshi, each containing: the market question, outcome probabilities, 24-hour trading volume, liquidity, closing timestamp, and a direct link to the market.

## 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"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/prediction-markets-aggregator-polymarket-kalshi-65fca0cc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x-402.online](https://www.zero.xyz/host/api.x-402.online/llms.txt)