Prediction Market Historical Data API (2026): OHLCV for Every Venue

What historical data do prediction market APIs provide?

Mostly price over time for each outcome, sometimes with volume and the bid and ask at each step. That is enough for charts, backtests, volatility studies and checking how a market reacted to news. Raw trade-by-trade history and full order book history are rarer and usually come from a data provider rather than the venue.

How do you get Polymarket and Kalshi price history?

This Node 18+ script pulls a week of history from each venue with no keys:

const day = 86400;
const now = Math.floor(Date.now() / 1000);

// Polymarket: price points for one outcome token
const [pm] = await (await fetch('https://gamma-api.polymarket.com/markets?limit=1&active=true&closed=false&order=volume24hr&ascending=false&liquidity_num_min=50000&end_date_min=2026-11-01')).json();
const token = pm.version === 'v2' ? pm.positionIds[0] : JSON.parse(pm.clobTokenIds)[0];
const { history } = await (await fetch(`https://clob.polymarket.com/prices-history?market=${token}&interval=1w&fidelity=60`)).json();
console.log('Polymarket', history.length, 'points, first', history[0], 'last', history.at(-1));

// Kalshi: hourly candles for one market over the last 7 days
const K = 'https://external-api.kalshi.com/trade-api/v2';
const { markets: [km] } = await (await fetch(`${K}/markets?status=open&limit=1&series_ticker=KXFEDDECISION`)).json();
const url = `${K}/series/KXFEDDECISION/markets/${km.ticker}/candlesticks?start_ts=${now - 7 * day}&end_ts=${now}&period_interval=60`;
const { candlesticks } = await (await fetch(url)).json();
const c = candlesticks.at(-1);
console.log('Kalshi', candlesticks.length, 'candles, last close', c.price.close_dollars ?? c.price.previous_dollars, 'yes ask close', c.yes_ask.close_dollars, 'volume', c.volume_fp);

// Kalshi: which endpoint holds older markets
console.log('Kalshi cutoff', (await (await fetch(`${K}/historical/cutoff`)).json()).market_settled_ts);

For deeper guides per venue, see Polymarket historical data and Kalshi historical data.

How do you get OHLCV for every venue in one call?

Predictefy's fetchOHLCV returns the same candle shape for 15+ venues. Ask by outcomeId, pick a resolution, and optionally a start and end:

import Predictefy from '@predictefy/sdk';

const client = new Predictefy({ apiKey: process.env.PREDICTEFY_API_KEY });

const [market] = await client.kalshi.fetchMarkets({ limit: 1, status: 'active' });
const outcomeId = market.outcomes[0].outcomeId;

const candles = await client.kalshi.fetchOHLCV({ outcomeId, resolution: '1h', limit: 500 });
for (const c of candles) {
  console.log(c.timestamp, c.open, c.high, c.low, c.close, c.volume, c.isTrueCandle);
}

How far back does Predictefy history go?

History replay, on Pro and above, streams stored data such as book snapshots and trades in time order as NDJSON pages through GET /v1/history/replay, which is how you rerun a past session tick by tick. For bulk files rather than API calls, see where to get prediction market datasets.

What can you build with historical prediction market data?

• Backtests of entry and exit rules on resolved markets.
• Charts for any market on any venue with one candle format.
• Event studies of how prices moved around debates, data releases or injuries.
• Calibration checks of how often a 70% price actually resolved Yes.

Past prices do not predict future results, and a strategy that worked in a backtest can lose money live.

Frequently Asked Questions