Polymarket Spread Arbitrage

Find and analyze arbitrage opportunities across prediction markets like Polymarket and Kalshi.

Cross-Platform Prediction Market Arbitrage ⚖️

Find arbitrage opportunities across prediction markets for autonomous agents. Powered by AIsa.

One API key. Match events across Polymarket and Kalshi to detect price discrepancies and potential risk-free profit opportunities.

What Can You Do?

Detect Price Discrepancies

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"Find the current price difference for the US election market between Polymarket and Kalshi."

Match Cross-Platform Markets

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"Find the Kalshi equivalent for this Polymarket sports event."

Track Arbitrage Spreads

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"Monitor the price spread for the upcoming NBA game across all supported prediction markets."

Analyze Orderbook Depth

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"Check the orderbook depth on both platforms to see if the arbitrage opportunity is actionable."

Quick Start

bash

export AISA_API_KEY="your-key"

How to Look Up IDs

Most endpoints require an ID from the /markets or /matching-markets responses. Always query markets first, then pass the relevant ID to downstream endpoints.

1. Polymarket token_id: Query /polymarket/markets, find side_a.id or side_b.id in the response, then use that value in the market price and orderbook endpoints.
2. Kalshi market_ticker: Query /kalshi/markets, find market_ticker in the response, then use that value in the market price and orderbook endpoints.

Core Capabilities

1. Find Matching Markets

The first step in arbitrage is finding the same event on multiple platforms.

Match by Event Ticker or Slug

bash

# Find equivalent markets across platforms using a Polymarket slug
curl -X GET "https://api.aisa.one/apis/v1/matching-markets/sports?polymarket_market_slug={polymarket_market_slug}" \
  -H "Authorization: Bearer $AISA_API_KEY"

# Or find equivalent markets using a Kalshi event ticker
curl -X GET "https://api.aisa.one/apis/v1/matching-markets/sports?kalshi_event_ticker={kalshi_event_ticker}" \
  -H "Authorization: Bearer $AISA_API_KEY"

Match Sports by Date

bash

# Find all matching sports markets across platforms for a specific date
curl -X GET "https://api.aisa.one/apis/v1/matching-markets/sports/{sport}?date={date}" \
  -H "Authorization: Bearer $AISA_API_KEY"

2. Compare Prices

Once matching markets are found, fetch the current prices on both platforms to calculate the spread.

Get Polymarket Price

bash

# token_id comes from side_a.id or side_b.id in /polymarket/markets response
curl -X GET "https://api.aisa.one/apis/v1/polymarket/market-price/{token_id}" \
  -H "Authorization: Bearer $AISA_API_KEY"

Get Kalshi Price

bash

# market_ticker comes from /kalshi/markets response
curl -X GET "https://api.aisa.one/apis/v1/kalshi/market-price/{market_ticker}" \
  -H "Authorization: Bearer $AISA_API_KEY"

3. Verify Liquidity

A price discrepancy is only actionable if there is enough liquidity to execute the trades.

Polymarket Orderbook

bash

# token_id comes from side_a.id or side_b.id in /polymarket/markets response
curl -X GET "https://api.aisa.one/apis/v1/polymarket/orderbooks?token_id={token_id}" \
  -H "Authorization: Bearer $AISA_API_KEY"

Kalshi Orderbook

bash

# ticker is the same value as market_ticker from /kalshi/markets response
curl -X GET "https://api.aisa.one/apis/v1/kalshi/orderbooks?ticker={ticker}" \
  -H "Authorization: Bearer $AISA_API_KEY"

API Endpoints Reference

Cross-Platform Endpoints

Endpoint	Description	Key Params
/matching-markets/sports	Find matching sports markets	polymarket_market_slug or kalshi_event_ticker
/matching-markets/sports/<sport>	Find sports markets by date	sport, date

Price and Liquidity Endpoints

Endpoint	Description	Key Params
/polymarket/market-price/<token_id>	Get Polymarket price	token_id, at_time
/kalshi/market-price/<market_ticker>	Get Kalshi price	market_ticker, at_time
/polymarket/orderbooks	Get Polymarket orderbook	token_id, start_time, end_time
/kalshi/orderbooks	Get Kalshi orderbook	ticker, start_time, end_time

Important Note About cURL Placeholders

The {...} values in the cURL examples are product-level placeholders and must be replaced before execution.

Execution constraint:

• Before running curl, the agent or runner must verify that every {...} placeholder has been replaced with a concrete value.
• If any placeholder such as {token_id}, {market_ticker}, {sport}, or {date} is still present in the final command, do not execute the command. Fail fast and surface a missing-parameter error instead.

This constraint is required because a literal brace placeholder may be interpreted by curl as URL globbing syntax rather than as plain text.

Understanding Arbitrage and Odds

• Prices as probabilities: Prices are usually shown as decimals, for example 0.65 means a 65% implied probability.
• Arbitrage opportunity: An opportunity exists when the combined price of all mutually exclusive outcomes across different platforms is less than 1.0. For example, if "Yes" is trading at 0.40 on Polymarket and "No" is trading at 0.55 on Kalshi, buying both guarantees a payout of 1.00 for a total cost of 0.95, before fees and slippage.
• Liquidity check: Always check the /orderbooks endpoints. A price difference might exist, but if the orderbook lacks depth, executing the trade may eliminate the profit.

Pricing

API	Cost
Prediction market read query	$0.01

Every response includes usage.cost and usage.credits_remaining.

Get Started

1. Sign up at aisa.one
2. Get your API key
3. Add credits (pay-as-you-go)
4. Set environment variable: export AISA_API_KEY="your-key"

Full API Reference

See API Reference for complete endpoint documentation.