Prediction Markets API

Prediction Markets API

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" }

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_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" }] }

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).

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