Prediction Market Arbitrage ⚖️

Find and analyze arbitrage opportunities across prediction markets such as Polymarket and Kalshi.

This skill helps agents:

• find matching markets across platforms
• compare current prices
• inspect orderbook depth and liquidity
• judge whether an apparent spread may be actionable

Powered by AIsa with a single AISA_API_KEY.

Use when

• You want to find the Kalshi or Polymarket equivalent of a market on another platform.
• You want to compare implied probabilities across platforms for the same event.
• You want to check whether a price gap is large enough to investigate as a possible arbitrage.
• You want to verify liquidity before treating a spread as actionable.

Compatibility

Works with any agentskills.io-compatible harness, including:

• Claude Code and Claude
• OpenAI Codex
• Cursor
• Gemini CLI
• OpenCode, Goose, OpenClaw, Hermes
• and other harnesses that implement the Agent Skills specification

Requires Python 3, a POSIX shell, and AISA_API_KEY from aisa.one.

Quick start

export AISA_API_KEY="your-key"

Example requests

Detect price discrepancies

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

Match cross-platform markets

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

Track arbitrage spreads

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

Analyze orderbook depth

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

How to look up IDs

Most endpoints require an ID from the /markets or /matching-markets responses. Query markets first, then pass the relevant ID into 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 analysis is finding the same event on multiple platforms.

Match by event ticker or slug

# 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

# 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

# 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

# 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

# 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

# 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

Price and liquidity endpoints

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

Get started

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

Full API reference

See API Reference for complete endpoint documentation.