Which prediction market platforms do you cover?

We currently support Kalshi, Polymarket, and Novig. All three are available on every plan, including the free Signal plan. Edge and Alpha add each new platform as it launches. We add platforms based on demand — contact us if you need something specific.

How is this different from integrating each platform directly?

Each platform has its own API, schema, authentication, and quirks. We normalize everything into a single consistent schema so you write one integration and get data from all platforms. We also handle rate limiting, uptime monitoring, and schema changes so you don't have to.

How fresh is the data?

Signal plan updates every 5 minutes. Edge plan offers sub-minute updates. Alpha plan provides the fastest available updates. WebSocket streaming is available on custom plans — contact us if you need a persistent connection rather than polling.

Can I access historical data for backtesting?

Yes. Historical records carry each market's opening odds, closing odds and resolved outcome, going back to January 2026. Edge includes the last 90 days, Alpha the full history. There is no tick-level price series — for that granularity you want the live feed, which timestamps every update.

Do I need a credit card to start?

No. The Free plan requires no credit card. Paid plans include a 7-day free trial — you can cancel anytime before being charged.

How do I authenticate my requests?

Include your API key in the X-Api-Key request header or as an apiKey query parameter. Your key is emailed to you after sign-up. Keep it secret — never expose it in frontend code.

What categories of prediction markets are available?

Coverage varies by platform but includes politics, economics, finance, science, weather, crypto, and world events. Use the category filter parameter to narrow results to topics relevant to your use case.

Now live — Polymarket, Kalshi + Novig unified feed

Prediction Market API.
One Unified Feed.

One API for every prediction market. Stop juggling fragmented feeds and get live odds, real-time prices, and historical data from Polymarket, Kalshi, and more through a single endpoint.

Get Your Free API Key Read the Docs →

Live Platforms

500k+

Active Markets

99.99%

Uptime

1B+

API Requests Served

Aggregating data from

PolymarketKalshiNovigMetaculusSoonPredictItSoon

Developer First

Up and running
in minutes

One endpoint, clean JSON, consistent schemas across every platform. No massaging raw data from multiple different APIs — you can make your first call in under a minute.

✓Normalized market schema across all platforms
✓WebSocket available for real-time data feeds
✓SDKs for Python, Java, and Go
✓OpenAPI prompt included

Explore the Docs →

Integrating a single platform first? Our guide to Polymarket's Gamma and CLOB APIs covers what that involves.

Polymarketpres-2028

KalshiPRES-28-D

Novigwho-wins-28

Metaculus#18204

PredictIt#7741

Prediction Market API

2028 Presidential Election Winner

5 platforms matched

arb availablenormalized

consensus_prob0.52

spread0.03

volume_24h$281k

The actual data

One request. Every platform, already matched.

The same underlying event carries a different identifier on every platform — a slug on Polymarket, a ticker on Kalshi, something else again on Novig. We resolve those to a single eventID before you ever see them, so comparing prices is a field lookup rather than a matching problem you have to solve yourself.

Request

curl "https://api.predictionmarketapi.com/v2/events\
  ?apiKey=YOUR_API_KEY\
  &bookmakerID=polymarket,kalshi,novig\
  &oddsAvailable=true\
  &limit=5"

Response200 OK

{
  "success": true,
  "data": [
    {
      "eventID": "US_PRESIDENTIAL_ELECTION_2028",
      "title": "Will the Democratic nominee win in 2028?",
      "leagueID": "US_POLITICS",
      "sportID": "PREDICTION_MARKETS",
      "status": {
        "started": false,
        "ended": false,
        "startsAt": "2028-11-07T05:00:00Z"
      },
      "odds": {
        "probability-home-game-ml-yes": {
          "oddID": "probability-home-game-ml-yes",
          "fairOdds": "+85",
          "bookOdds": "+88",
          "byBookmaker": {
            "polymarket": { "odds": "+85", "available": true },
            "kalshi":     { "odds": "+88", "available": true },
            "novig":      { "odds": "+92", "available": true }
          }
        }
      }
    }
  ]
}

Every platform's price for that outcome arrives under byBookmaker in one object — that spread between +85 and +92 is the thing arbitrage tools exist to find. See the full schema for every field an event carries.

What's included

Everything you need to build

Unified Market Feed

Normalized data across Polymarket, Kalshi, Novig, and more — one integration, every platform.

Pre-Match & In-Play Odds

Full odds coverage from market open through resolution. Pre-match lines and live in-play prices updated in real time.

Scores & Settlements

Every market includes resolution outcomes and settlement data — everything you need to determine results and label training data.

Historical Data

Opening and closing odds plus resolved outcomes for every finalized market, back to January 2026.

Consensus Pricing

Aggregate implied probabilities across platforms. Build your own no-vig reference price.

RESTful & WebSocket APIs

Pull data on demand via REST or subscribe to real-time streams via WebSocket. One integration, two access patterns.

Backtesting or training a model? See exactly what the historical archive covers — opening odds, closing odds and resolved outcomes back to January 2026.

Coverage

What each platform actually brings

3platforms live today, two more in progress. They are not interchangeable — each one is stronger in a different category, which is the whole reason a cross-platform price is worth more than any single venue's.

PolymarketLive

The largest platform by volume. Deep liquidity on politics and macro, plus sports, crypto and culture markets. Settled on Polygon.

KalshiLive

A CFTC-regulated US exchange. Narrower selection than Polymarket, weighted toward politics, economics and weather, and often the sharper price on economic indicators.

NovigLive

Sports-first, and more granular there than the others — individual game lines and player markets you will not find elsewhere.

MetaculusSoon

Community forecasting rather than trading. Useful as a second opinion on long-horizon questions where the money markets are thin.

PredictItSoon

US political markets with a long history. Regulatory constraints cap position sizes, which keeps the selection narrow.

Prices diverge between these venues more often than you would expect, and we compared the three live platforms head to head to show where and why.

Build vs integrate

You can build this yourself. Most teams stop enjoying it around the second platform.

Writing one integration is a good weekend. The work that follows is the part people underestimate: keeping five schemas aligned, and keeping the mapping between them correct as platforms add, rename and retire markets.

The job	Doing it yourself	With one API
Integrations to write	One per platform, each with its own quirks	One, against a single endpoint
Authentication	A different model each time — public reads here, API keys there, signed requests elsewhere	One API key in one header
Schemas to normalise	Every platform names and nests its fields differently	One schema, identical across platforms
Matching an event across platforms	Your own logic, rebuilt whenever a platform splits or renames a market	Resolved for you and returned under one eventID
Rate limits	Track and respect a separate budget per platform	One limit, visible on your usage endpoint
When a platform changes its API	You find out when something breaks in production	We absorb the change behind the same schema
Historical data	Poll, store and backfill it yourself from day one	90 days on Edge, the full archive on Alpha
Time to first useful data	Weeks, then ongoing maintenance	Minutes

If you only ever need one platform, going direct is genuinely the right call — our Polymarket API guide walks through exactly how. It's the second platform where the arithmetic changes.

Pricing

Start free, scale with confidence

Signal

The easiest way to start building with prediction market data.

✓2,000 entities per month

✓10 requests per minute

✓5 min update frequency

✓3 platforms

✓Community support

What will you build?

Builders across the prediction market ecosystem rely on our data infrastructure.

Arbitrage & Value Tools

—Cross-platform scanners
—Implied probability comparisons
—Kelly criterion calculators
—Alert pipelines

ML & Quant Models

—Historical training datasets
—Real-time feature feeds
—Outcome labeling
—Backtesting infrastructure

Prediction Platforms

—Consensus price feeds
—Market discovery
—Resolution data
—Liquidity metrics

Research & Media

—Embed live markets
—Forecast aggregation
—Academic datasets
—Editorial dashboards

Building a scanner? See what cross-platform arbitrage data actually gives you — matched markets, and an honest account of what it can't tell you.

Who's behind it

Data infrastructure is a trust purchase

You are about to make something you own depend on something we run. That is a fair thing to be careful about, so here is what we would want to know in your position.

This is not our first odds API

The feed runs on the same infrastructure behind SportsGameOdds, which has been serving normalised odds data to developers for years. Prediction markets are a new surface on a pipeline that already exists, not a first attempt at building one.

Built in Austin by an odds-data team

A small team that has spent its working life on odds infrastructure — ingestion, normalisation and keeping feeds correct when upstream sources change without warning. More about us.

You can reach a person

Email support on paid plans, a Discord channel for Edge and Alpha, and a contact form that reaches a founder rather than a ticket queue. Small enough that this is still true.

Free means free, not a trial

The Signal plan has no card requirement and no expiry date. Build against it for as long as you like and move up only when the limits bite.

FAQ

Common questions

Start building today

Free plan, no credit card required. Full API access from day one.

Get Your Free API Key Talk to a founder

Prediction Market API.One Unified Feed.

Up and runningin minutes