Prediction Markets API

![MCP Server](https://prediction-markets.api.klymax402.com/mcp) ![x402](https://x402.org) ![License: MIT](LICENSE)

Real-time prediction market odds from Polymarket and Kalshi. Active markets, probabilities, volume, categories. The betting intelligence layer agents need for event forecasting. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "prediction-markets": {
      "url": "https://prediction-markets.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl -X POST "https://prediction-markets.api.klymax402.com/api/markets" \
  -H "Content-Type: application/json" \
  -d '{}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

| Tool | Method | Path | Price | Description | |---|---|---|---|---| | prediction_list_markets | POST | /api/markets | $0.012 | List active prediction markets from Polymarket and Kalshi with current odds, volume, and categories. Filter by topic, platform, and sort by volume, newest, or closing soon. | | prediction_get_market_odds | POST | /api/odds | $0.012 | Get detailed odds and trading data for a specific prediction market by ID or search query. Searches both Polymarket and Kalshi. | | prediction_trending_markets | POST | /api/trending | $0.008 | Top trending prediction markets from Polymarket and Kalshi ranked by volume and engagement. |

`prediction_list_markets`

Use this when you need to browse active prediction markets or find betting odds on real-world events. Returns a list of active markets from Polymarket and Kalshi with current probabilities, trading volume, and metadata.

Parameters

| Name | Type | Required | Description | |---|---|---|---| | category | string | no | Filter markets by topic category. Omit for all categories. | | limit | number | no | Number of markets to return (1-50). Default: 20. | | sort | string | no | Sort order. 'volume' = highest traded, 'newest' = recently created, 'closing_soon' = ending soonest. Default: volume. | | source | string | no | Filter by platform. Omit to get markets from both Polymarket and Kalshi. |

Returns

question -- the prediction market question (e.g. "Will Bitcoin reach $100k by December 2026?")
outcomePrices -- probability for each outcome as decimal (0.65 = 65% chance YES)
volume -- total trading volume in USD
liquidity -- current available liquidity in USD
endDate -- when the market resolves
category -- topic category (politics, crypto, sports, science, culture)
active -- whether the market is currently trading
source -- data source -- "polymarket" or "kalshi"

Example response:

{ markets: [{ question: "Will Trump win 2028?", outcomePrices: { "Yes": 0.42, "No": 0.58 }, volume: 15420000, liquidity: 890000, endDate: "2028-11-06", category: "politics", source: "polymarket" }] }

Not for: crypto price data (use token_get_price), crypto news (use crypto_get_news), stock prices (use stock_get_quote), DeFi yields (use defi_find_best_yields), Hyperliquid perp data (use hyperliquid_get_market_data).

`prediction_get_market_odds`

Use this when you need detailed odds, probabilities, and trading data for a specific prediction market. Searches both Polymarket and Kalshi to find the best match by market ID or question text.

Parameters

| Name | Type | Required | Description | |---|---|---|---| | marketId | string | no | Polymarket condition ID or Kalshi ticker. Use this if you already know the market ID. | | query | string | no | Search query to find a market by question text (e.g. 'bitcoin 100k', 'trump election'). Used when marketId is not known. |

Returns

question -- the full prediction market question text
outcomes -- array of possible outcomes with their current probabilities
outcomePrices -- decimal probabilities per outcome (0.72 = 72% implied probability)
volume -- total all-time trading volume in USD
volume24h -- trading volume in the last 24 hours
liquidity -- current depth of the order book in USD
endDate -- resolution date of the market
description -- detailed market description and resolution criteria
active -- whether the market is currently open for trading
source -- which platform the market is from -- "polymarket" or "kalshi"

Example response:

{ question: "Will ETH flip BTC by 2027?", outcomes: ["Yes", "No"], outcomePrices: { "Yes": 0.08, "No": 0.92 }, volume: 2340000, volume24h: 45000, liquidity: 120000, endDate: "2027-12-31", active: true, source: "polymarket" }

`prediction_trending_markets`

Use this when you need to see what prediction markets are trending right now. Returns the hottest markets from both Polymarket and Kalshi ranked by recent trading volume and activity.

Parameters

| Name | Type | Required | Description | |---|---|---|---| | limit | number | no | Number of trending markets to return (1-30). Default: 10. | | source | string | no | Filter by platform. Omit to get trending markets from both Polymarket and Kalshi. |

Returns

question -- the market question
probability -- current implied probability for the leading outcome (decimal)
volume24h -- trading volume in the last 24 hours in USD
totalVolume -- all-time trading volume in USD
priceChange24h -- change in probability over the last 24 hours (e.g. +0.05 = probability rose 5%)
category -- topic category
endDate -- when the market resolves
source -- data source -- "polymarket" or "kalshi"

Example response:

{ trending: [{ question: "Will Fed cut rates in July 2026?", probability: 0.73, volume24h: 890000, totalVolume: 12500000, priceChange24h: 0.08, category: "politics", endDate: "2026-07-31", source: "polymarket" }] }

Example agent prompts

"Browse active prediction markets or find betting odds on real-world events"
"Detailed odds, probabilities, and trading data for a specific prediction market"
"See what prediction markets are trending right now"

Payment

Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
Network: Base L2 (eip155:8453)
Asset: USDC
Facilitator: Coinbase CDP (primary), PayAI (fallback)
Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

Catalog: https://klymax402.com/llms.txt
Full API reference: https://klymax402.com/llms-full.txt
Live stats: https://klymax402.com/stats

License

MIT

Prediction Markets API