Kalshi API — Markets, Order Book & Trades
Pricing
Pay per event
Kalshi API — Markets, Order Book & Trades
Live data from Kalshi, the CFTC-regulated US prediction market: market odds ranked by volume, full L2 order-book depth, and executed trades with volume-weighted average price. No login, no API key, no account required.
Kalshi API — Markets · Order Book · Trades
Live data from Kalshi, the CFTC-regulated US prediction market. Market odds ranked by traded volume, full L2 order-book depth, and executed trades with a volume-weighted average price. All public data — no login, no API key, no account.
Three datasets, priced separately
| Mode | What you get | Price |
|---|---|---|
markets | Live odds, ranked by traded volume | $0.005 per market |
orderbook | Every bid and ask level with size | $0.02 per snapshot |
fills | Executed trades with aggressor side | $0.002 per trade |
You only pay for rows you actually receive.
Markets
Ranked by volume, because "the top 50 Kalshi markets" should mean the ones people trade. Kalshi's own flat market listing is dominated by untraded multi-leg parlay legs — of the first 1,200 it returns, 64 had any volume at all. This actor reads the event-level API instead, where 627 of 803 markets sampled were actively traded.
| Field | Description |
|---|---|
ticker | Unique market id, e.g. KXELONMARS-99 — use this for the other two modes |
question | Self-identifying question text (see note below) |
subtitle | What a YES resolves to, when one question is split across outcomes |
yesPrice, noPrice | Implied probability, 0..1 |
spread | Bid/ask gap |
volume, openInterest | Contracts traded / contracts outstanding |
volumeUnit | Always contracts here. Polymarket's volume is dollars — the field says which you have, so a cross-venue query cannot silently compare the two. |
closeTime, status, resolvedOutcome | Lifecycle |
On question: Kalshi splits multi-outcome questions into one market per outcome and gives
them all the same title — 138 of 803 live markets shared their title with another market, so two
rows would read identically at different prices. Worse, some titles arrive with the subject
missing ("Will become President of the United States?"). This actor rebuilds the question from
the event so every row identifies itself. ticker remains the unique key.
Order book
Full L2 depth, normalized to 0..1 probability. Kalshi quotes both sides as bids, so a resting no-bid at 0.17 is published here as a yes-ask at 0.83 — the book reads like any other exchange's.
bestBid, bestAsk, midPrice, spread, plus bids[] and asks[] with price and size.
A book with no bids and no asks is not returned and not charged. An empty book is indistinguishable from a broken parser, so this actor treats it as a failure worth telling you about rather than a row worth billing.
Trades
| Field | Description |
|---|---|
yesPrice, noPrice | The probability this trade printed at |
count | Contracts (each settles at $1) |
value | What the YES buyer paid |
takerSide | Which side was the aggressor — the direction that moved the price |
isBlockTrade | Negotiated off-book size |
ts | Venue timestamp |
Each trade carries a summary with count, contracts, volume, aggressor split, and a single
volume-weighted average price. That single VWAP is honest here — verified across 600 live
trades, a Kalshi market's no price is always exactly 1 - yes, so there is one price series.
Block trades are excluded from the VWAP because they print away from the book.
⚠️ The VWAP covers exactly the trades you fetched, and trades come newest-first. It is not the
market's lifetime average unless you asked for enough rows to reach the market's first trade.
Measured on KXALIENS-27: the newest 100 trades average 0.0725, all 26,910 average
0.1207 — the same field, 40% apart. The summary therefore carries oldestTradeAt,
newestTradeAt and truncated, so you can always see which window you are looking at. If
truncated is true, raise Max results to go further back.
Limits, stated up front
- No wallet or transaction hash. Kalshi is a regulated exchange, not a blockchain. Wallet-level whale tracking is not possible here — that is a Polymarket-only capability.
liquidityis alwaysnull. Kalshi's API returned 0.0000 for it on all 803 markets sampled, including one with 167k volume. Reporting 0 would claim a market has no liquidity when it has a deep book, so this actor reports nothing rather than something false.- Snapshots, not a stream. Each run captures a moment.
Use cases
Quant research and backtesting, odds aggregation, cross-venue arbitrage against Polymarket, market-making analytics, AI agents that need live probability data.
For the developer (not shown on the Store)
Thin wrapper over the private scraper-gateway; contains no scraping logic. Set Actor
environment variables (secret): SCRGW_URL, SCRGW_SECRET. Pay-per-event events:
market-returned ($0.005), orderbook-snapshot ($0.02), fill-returned ($0.002).
Deploy: apify push --force.
