Prediction markets API

How much is trading on prediction venues, per venue and combined?

Per venue and combined: 24-hour and all-time volume (contracts on kalshi, USD on polymarket), trade count, active and total markets, and unique traders where reported. No open interest.

GET/api/external/prediction/prediction-overview

Get a free API key Try it in the API reference

What it returns

One row per prediction venue with its market counts, trade count, traded volume on record and over the last 24 hours, and its unique trader count, plus the same figures for every venue together. Volume is in each venue's own unit, named by volumeUnit: contracts on kalshi, USD on polymarket; the …Usd fields are null where the volume is not USD, and the combined USD volume is null while the venues' units differ. uniqueTraders is null for a venue that does not report it; there is no combined trader count, because the same trader cannot be matched across venues. Open interest is not published: no figure for it is available. activeMarkets is counted differently from the one in the prediction venue schedule, so the two do not match. No chain and no subject.

Chains

This endpoint is not tied to a chain: it takes no chain in its request.

Request

Send your key in the x-dex-data-key header. Replace each <placeholder> with a real value.

curl -H "x-dex-data-key: $DEXDATA_API_KEY" \
  "https://api.dexdata.io/api/external/prediction/prediction-overview"

Response fields

A JSON response. Every field is always present; null means the value could not be established, never zero.

Response fields of How much is trading on prediction venues, per venue and combined?
Field	Type	Description
`venues`	object[]	One row per venue. The set is open: a new venue appears as a new row.
`venues[].venue`	string	The venue, lowercase, e.g. `kalshi` or `polymarket`.
`venues[].activeMarkets`	integer	Markets the venue counts as active.
`venues[].totalMarkets`	integer	Every market the venue has listed, open or settled.
`venues[].totalTrades`	integer	Every trade on record.
`venues[].totalVolume`	number	Traded volume on record, in `volumeUnit`.
`venues[].volume24h`	number	Traded volume over the last 24 hours, in `volumeUnit`.
`venues[].volumeUnit`	string \| null	The unit of `totalVolume` and `volume24h`: `contracts` (number of contracts traded, one contract settling at $1) on `kalshi`, `usd` on `polymarket`. Null for a venue whose unit is not known yet.
`venues[].totalVolumeUsd`	number \| null	Traded volume on record in USD. Null when the venue's volume is not in USD.
`venues[].volume24hUsd`	number \| null	Traded volume over the last 24 hours in USD. Null when the venue's volume is not in USD.
`venues[].uniqueTraders`	integer \| null	Distinct traders on record. Null when the venue does not report it, never a fake 0.
`combined`	object	Every venue together. `activeMarkets` is the sum of the venue counts.
`combined.activeMarkets`	integer	Markets the venue counts as active.
`combined.totalMarkets`	integer	Every market the venue has listed, open or settled.
`combined.totalTrades`	integer	Every trade on record.
`combined.totalVolumeUsd`	number \| null	Traded volume on record across every venue, USD. Null unless every venue's volume is in USD.
`combined.volume24hUsd`	number \| null	Traded volume over the last 24 hours across every venue, USD. Null unless every venue's volume is in USD.

Price per call

Every call: 18 credits

Charged only when the call succeeds. Prices as of 2026-10-30; the current ones are always in the API reference.

Is each prediction venue open and trading right now?
A venue whose 24-hour volume collapses may be closed or in maintenance.
Which prediction markets, events or traders match this text?
Free-text search across prediction venues: matching markets, events and traders, with ids and close dates. Identity only, no prices or volume.
One prediction-market trader's newest buys and sells
What one prediction-market trader just bought and sold, fill by fill, newest first: price, shares, the outcome, and the market and event of each. Polymarket traders only.
Which prediction market is on this venue page?
Resolve a prediction market page slug (or a ticker) to the market: its venue id, title, event, outcome labels and close date. Identity only, no prices or volume.
Which prediction-market categories carry the most volume on each venue?
Per venue, each category tag with its market count and all-time volume, highest first. Volume is in the venue's own unit: contracts on kalshi, USD on polymarket.
Which sports leagues can I find prediction markets for?
The sports leagues a prediction venue lists markets under: league code, the venue's own league, series and tag ids, settlement source and logo.

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