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Probability infrastructure for prediction markets

Cross-venue normalized probability distributions across Kalshi and Polymarket. Real-time orderbooks, trade executions, and historical archives. Built for macro desks, quant research, and anyone modeling event outcomes.

Get API Key For Institutions

Search 700K+ markets on Explore

Two exchanges. Two APIs.
Zero standardization.

You want to know if the Fed will cut rates in June. Kalshi gives you KXFEDDECISION-26JUN-H0. Polymarket gives you 0x3f8a0c9b.... Different IDs, different orderbooks, different WebSocket protocols. You can spend a month building the normalization layer yourself.

KALSHI

GET /markets/KXFEDDECISION-26JUN-H0

{
  "ticker": "KXFEDDECISION-26JUN-H0",
  "yes_ask": 0.94,
  "no_ask": 0.07,
  "volume": 4714197,
  "open_interest": 891003
}

POLYMARKET

GET /markets/0x3f8a0c9b7e...

{
  "condition_id": "0x3f8a0c9b...",
  "tokens": [{ "token_id": "635866..." }],
  "outcome_prices": ["0.955","0.045"],
  "volume": "1965879.48"
}

ODDPOOLone query, both venues

GET /search/events?q=fed+rate+june

[{
  "event_id": "KXFEDDECISION-26JUN",
  "exchange": "kalshi",
  "title": "Fed Rate Decision June",
  "total_volume": 4714197
}, {
  "exchange": "polymarket",
  "title": "FOMC June 2026",
  "total_volume": 1965879
}]

Or you search once and get both. Then pull historical orderbooks, track whale trades, and find cross-venue arbitrage. All from one API key.

FREE ON EVERY TIER

700,000 markets.
One search.

Every active market on Kalshi and Polymarket, indexed and searchable. Filter by venue, category, volume, or liquidity. Find markets that don't show up in either exchange's own search. Get event-level groupings with all their underlying markets in a single call.

# search events across both venues
curl "https://api.oddpool.com/search/events?
  q=bitcoin&status=active&sort_by=volume&limit=5"
  -H "X-API-Key: oddpool_abc123"

# returns events from both Kalshi and Polymarket
# with market_count, total_volume, total_liquidity
# also: /search/markets for individual contracts
# also: /search/recent/events for newly listed

FREE ON EVERY TIER

Orderbooks back
to March 2026.

Full-depth orderbook snapshots, top-of-book timeseries, and trade tapes for every Kalshi and Polymarket market. 1-minute or 5-minute granularity. Cursor-paginated so you can download the entire history for any market. Backtest your model against real microstructure.

historical

# full orderbook snapshots
curl "https://api.oddpool.com/historical/
  kalshi/orderbook?
  market_id=KXFEDDECISION-26JUN-H0&
  granularity=1m&limit=100"
  -H "X-API-Key: oddpool_abc123"

# returns yes_bids, no_bids, best_yes_bid,
# best_yes_ask, mid, spread for each snapshot
# also: /top-of-book, /trades
# also: /historical/polymarket/* for Poly markets

Full API docsAI-agent ready at api.oddpool.com/llms.txt

WHALE TRACKINGPro $30/mo

See the smart money
before the market does.

Every trade over $500 on both Kalshi and Polymarket, flagged and delivered in real time. Filter by event, platform, and minimum size. Last week, 151 whale trades totaling $185K in 24 hours on a single event. When someone drops $15,000 on "Fed holds rate" at 95¢, you'll know about it.

whale feed

{
  "platform": "polymarket",
  "event_title": "FOMC June 2026",
  "market_title": "Fed holds rate",
  "taker_side": "yes",
  "trade_size_usd": 15000.00,
  "price": 0.95,
  "timestamp": "2026-03-22T14:30:00Z"
}

ARBITRAGEPremium $100/mo

When venues disagree,
you profit.

The arbitrage endpoint scans every matched market across both venues and returns opportunities with net profit after fees already calculated. Kalshi says 42¢, Polymarket says 39¢. Buy YES on Poly, buy NO on Kalshi. That's a guaranteed 1¢ per contract. A single 3¢ arb on 100 contracts is $3. Pro users spotted 762 arb opportunities last week alone.

arbitrage opportunity

{
  "event_title": "Fed rate decision June",
  "label": "25bps cut",
  "buy_yes_market": "polymarket",
  "buy_no_market": "kalshi",
  "kalshi": { "yes_ask": 0.42, "volume": 150000 },
  "polymarket": { "yes_ask": 0.39, "volume": 200000 },
  "gross_cents": 1.0,
  "fee_cents": 0,
  "net_cents": 1.0
}

ONE PROMPT. THAT'S IT.

Your coding agent already
knows how to use this.

Drop the link into Claude, GPT, Cursor, or any coding agent. It reads the full API reference and starts writing working code against Oddpool instantly. No docs to skim. No SDK to install.

prompt

Read https://docs.oddpool.com/llms.txt

Use my API key oddpool_abc123 to

search for bitcoin markets and pull the latest orderbook for the top result.

wss://feeds.oddpool.com/ws

Know what the market thinks
before the data drops.

FOMC meeting tomorrow? Watch the probability shift in real time as both Kalshi and Polymarket reprice. CPI print at 8:30am? See the market's reaction across venues in a single normalized stream. Our Macro Feed gives you liquidity-weighted cross-venue probabilities for every major economic event, with full orderbook depth and trade execution data.

Four channel types: dist for probabilities (free), plus book, trade, and snapshot for full microstructure. One WebSocket connection, one subscribe message, data starts flowing.

FOMCCPIPayrollsGDPUnemployment

Crypto and weather feeds in development, each enriched with domain-specific data.

wss://feeds.oddpool.com/ws

distfomc-2026-06-17hold prob=0.948 kalshi=0.945 poly=0.955

bookfomc-2026-06-17polymarket yes bid=0.955 ask=0.965 spread=0.010

tradefomc-2026-06-17kalshi buy no qty=136 @ 0.06

distcpi-2026-05above_3.5% prob=0.221 kalshi=0.215 poly=0.230

bookcpi-2026-05kalshi yes bid=0.215 ask=0.230 spread=0.015

tradefomc-2026-06-17polymarket sell no qty=8300 @ 0.045

distnfp-2026-06above_200K prob=0.613 kalshi=0.605 poly=0.625

FREE FOREVER

Not a developer?
We built the dashboards too.

750+ live event dashboards across politics, sports, crypto, economics, and culture. Cross-venue search across 700K+ markets. Historical charts. Paper trading. No account required.

Fed Market Watch Bitcoin Peak NBA Champion FIFA World Cup Venue Dominance Super Bowl LX

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