Prediction-market data API
Kalshi, Polymarket, Hyperliquid and seven more venues behind one API key. Search every market, read live prices and fees, and match the same game across venues, all in one format.
Free plan: every endpoint, 1,000 requests a month, no card.
Kalshi
170,733
markets
Polymarket
423,368
markets
Predict
16,190
markets
SX.Bet
14,925
markets
Hyperliquid
306
markets
AlphaArcade
1,288
markets
ProphetX
10,136
markets
Limitless
549
markets
Pred
4,246
markets
Polymarket US
90,552
markets
732,293 markets in GET /v1/markets on Oct 30, 2026
01/use cases
One integration instead of ten. If your product needs to know what prediction markets are saying, this is the data layer under it.
Find the same game on every venue that lists it, then read each venue's price side by side. Tie and overtime rules come with it, so you compare like with like.
/v1/matching-markets/sports/v1/markets/{market_id}
Search every market in politics, economics, crypto, sports and more, in one format, filtered by venue and category.
/v1/markets
Live bid, ask and fees, read from the venue on every call.
/v1/markets/{market_id}
Open positions for any Polymarket wallet, by address or username.
/v1/polymarket/wallet/positions
Typed SDKs, a public OpenAPI spec and llms.txt your agent can read.
llms.txtopenapi.yaml
Per-second Binance prices for any pair, for backtests and settlement checks.
/v1/crypto-prices/binance
02/catalog
Politics, economics, crypto, finance, technology, weather and culture: every venue's markets in one list, in one row format, filterable by venue and category. Paging walks one fixed snapshot, so results never shift between pages.
Will the Democratic party win the House in 2028?
kalshi:CONTROLH-2028-D
Will Trump recognize Somaliland before 2027?
polymarket:1029715
Will the Democratic Party control the Senate after the 2026 Midterm elections?
predict:12140
Presidential Election Winner 2028
alpha-arcade:01K0HQDM64MEEWPTRWQ60HMTH8
Rows are examples from several venues. One request walks the venues in a fixed order, so add &provider= to start on one. Counts as of Oct 30, 2026.
03/live prices
Ask for any market and we read it from its venue right then. Every price comes back as a probability from 0 to 1, with the bid, the ask and what it costs to trade, and an empty field, never a guess, where a venue doesn't say.
A 67% chance, as each venue sends it10 formats
Kalshi
"0.6700"
dollars, as text
Polymarket
"[\"0.67\", \"0.33\"]"
a list inside text
Predict
0.67
a plain decimal
SX.Bet
"67000000000000000000"
times 10²⁰, as text
Hyperliquid
"0.67"
book price, as text
AlphaArcade
670000
millionths of a dollar
ProphetX
-203
American odds
Limitless
[67, 33]
percent, both sides
Pred
"67"
cents, as text
Polymarket US
{"value":"0.6700","currency":"USD"}
an amount in dollars, with its currency
You get
0.67
"price": 0.67
One number from 0 to 1 on every venue, with the bid, ask and last trade beside it where the venue has them.
{"id": "kalshi:CHINAUSGDP-30","provider": "kalshi","title": "Will China overtake US GDP by 2030?","status": "open","outcomes": [{ "name": "Yes", "price": 0.145, "bid": 0.13, "ask": 0.16 },{ "name": "No", "price": 0.855, "bid": 0.84, "ask": 0.87 }],"pricing": {1"availability": "live","source": "market_record","as_of": "2026-04-09T09:18:12.024186Z",2"as_of_kind": "record_static","observed_at": "2026-10-12T17:42:57.523Z"},3"volume_24h_usd": null,"volume_24h_contracts": 5.39,"trading_fees": {"availability": "published","taker": {4"model": "quadratic","rate": 0.07,"exponent": 1},"maker": {"model": "none","rate": 0}}}
Can you trade at this price?
live means the venue has a real bid and ask on its book right now. A lone side, an old mark with no book behind it, or a book wider than the venue's own spread rule reads indicative instead.
How old is the quote?
Kalshi's as_of is a record write that hasn't moved in six months, though this market is open and quoted. We label it record_static and add observed_at, the moment we read it, so you know which time to trust.
Empty beats invented
Kalshi counts volume in contracts, not dollars. The dollar field stays null and the contract count sits beside it, rather than a number converted at a price we would have to make up.
What a trade costs
Kalshi's fee is 7% × price × (1 − price) per contract, so it peaks at 50¢. At this market's 16¢ ask, 100 contracts cost about 94¢ in fees. The chart below draws the whole curve.
Kalshi charges the most at 50¢ and almost nothing near 0¢ or $1. The API returns the formula and the rate, so you can price an order before you place it.
04/sports matching
The same game is listed under a different name, id and sometimes date on every venue. Matching joins the listings into one event, so you can compare prices side by side, and checks the fine print, like what each venue does if the game ends in a tie.
nfl-sea-den-2026-10-15
moneyline|full|winner
winner:sea · winner:den
kalshi KXNFLGAME-26OCT15SEADEN-DEN ──┐kalshi KXNFLGAME-26OCT15SEADEN-SEA ──┤polymarket 4212356 ──┤predict 1966227 ──┤sxbet 0x9228…b384 ──┼──▶ nfl-sea-den-2026-10-15prophetx 1700008795:219 ──┤ moneyline|full|winnerpred 0x9cad…:0x… ──┤ winner:sea · winner:denlimitless seahawks-vs-broncos-… ──┤hyperliquid 11446 ──┘
8 venues · 171 matched markets on this game: winner, spreads, totals and more · each venue keeps its own ids
| venue | if tied | overtime | in their words |
|---|---|---|---|
| Kalshi | pays half"$0.50 for each team" | counts | "$0.50 for each team" |
| Polymarket | pays half"resolve 50-50" | counts | "resolve 50-50" |
| Predict | pays half"resolve 50-50" | counts | "resolve 50-50" |
| Limitless | pays half"resolve 50-50" | counts | "resolve 50-50" |
| Hyperliquid | pays half"resolves to 0.5" | counts | "resolves to 0.5" |
| Pred | pays half"resolve 50-50" | counts | "resolve 50-50" |
| ProphetX | voids the bet"shall be void" | counts | "shall be void" |
| SX.Bet | voids the bet"outcome": 0 | counts | "outcome": 0 |
| Across venues | differs | same |
Six venues pay half on a tied NFL game; two void the bet. So the API marks this game's moneyline settlement_equivalence: "different", with each venue's evidence behind every value.
One id per game
nfl-sea-den-2026-10-15
League, away team, home team and the date in Eastern time, so a game keeps one id whatever date each venue files it under.
Find it from any venue's id
source_id=sxbet:L19431555
Already hold a Kalshi ticker or a Polymarket slug? Send it to the lookup and get the whole matched game back, up to 100 ids at a time.
Not just who wins
spread|half:1|spread:jax|2.5
Spreads, totals, team totals, halves and quarters, and verified player props, each with its own stable key.
| venue | NBA | WNBA | NHL | MLB | NFL |
|---|---|---|---|---|---|
| Kalshi | |||||
| Polymarket | |||||
| Predict | · | ||||
| SX.Bet | |||||
| Hyperliquid | · | · | · | · | |
| AlphaArcade | |||||
| ProphetX | |||||
| Limitless | · | · | · | · | |
| Pred | · | · | · | ||
| Polymarket US |
| league | Kalshi | Polymarket | Predict | SX.Bet | Hyperliquid | AlphaArcade | ProphetX | Limitless | Pred | Polymarket US |
|---|---|---|---|---|---|---|---|---|---|---|
| NBA | · | · | ||||||||
| WNBA | · | · | · | · | ||||||
| NHL | · | · | · | |||||||
| MLB | · | · | · | |||||||
| NFL |
A filled square means the venue is mapped for that league; a game carries the venues that list it. Every venue market, matched or not, stays available in /v1/markets.
05/endpoints
Read-only, one API key, one error format. Every endpoint is on the free plan.
Catalog
providercategorylimitcursorMarket data
providerproviderMatching
leaguescheduled_dateparticipantinclude_submarketsinclude_rulesinclude_settledevent_idsource_idWallets & prices
addressusernamelimitcursoraddressusernamecurrencystart_timeend_timecursor06/sdks
TypeScript, Python and Go clients come from the same OpenAPI spec as the API, so every field is typed the day it ships. Or call it from anything that speaks HTTP.
$ npm install @predictorsdk/client1import { PredictorSDKClient } from "@predictorsdk/client";23const client = new PredictorSDKClient({ token: "YOUR_API_KEY" });45// Every venue's economics markets, in one row shape.6const page = await client.getMarkets({ category: "economics", limit: 5 });78// A row id is "{provider}:{native_id}", so it pipes straight into detail.9const market = await client.getMarket({ marketId: page.data[0].id });1011console.log(market.title, market.outcomes[0].price, market.pricing.availability);12// Will China overtake US GDP by 2030? 0.145 live
Cursors, walked for you
for await (const m of page)
Every paginated call returns a pager; iterate it and the client follows the cursor and keeps your filters.
One error shape
{ "code": "ambiguous_identifier", … }
Stable machine-readable codes on every error. An id two venues share answers 409 with both candidates, never a guess.
Retries and request ids
X-Request-Id: req_…
Clients retry 408, 429, 5xx and dropped connections. Every response carries an X-Request-Id, and rate-limit headers say when to back off.
Built for agents too
llms.txt · openapi.yaml
The docs ship as llms.txt and the full OpenAPI spec, the same one the SDKs are generated from.
07/pricing
Every plan includes every endpoint. Paid plans add requests and speed, not features, and nothing changes in your code when you upgrade.
| Plan | Price | Requests | Per min |
|---|---|---|---|
| Free | $0/mo | 1K | 10 |
| Starter | $29/mo | 100K | 60 |
| ProPopular | $79/mo | 500K | 300 |
| Business | $199/mo | 2M | 1,000 |
| Enterprise | Custom | custom | custom |
Free
$0/ mo
Starter
$29/ mo
ProPopular
$79/ mo
Business
$199/ mo
Enterprise
Custom
Requests are per month. Paid plans continue past their allowance at a small per-request rate.
08/faq
09/get started
The free plan covers every endpoint at 1,000 requests a month, with no card. Paid plans add throughput, not features.
Building something bigger, or want to talk it through? nick@predictorsdk.com