Free Prediction Market Data API — Real-Time Polymarket Odds, Signals & Sentiment from 28+ Sources

#api #webdev #javascript #python

Ever wanted real-time prediction market data without scraping? I built Sirius API — a free REST API that gives you live Polymarket odds, algorithmic trading signals, sentiment analysis, and more.

What you get (Free tier)

Live markets — all active Polymarket markets with current odds
Trading signals — 2,500+ signals/day from 6 detection layers (15-min delay on Free)
Sentiment analysis — crypto Fear & Greed index, long/short ratios
Sports odds — NBA, NFL, NHL, NCAA, soccer from ESPN + Kalshi
Weather forecasts — NOAA data matched to prediction markets
Cross-platform comparison — Polymarket vs Kalshi vs PredictIt odds

Data Sources (28+)

Polymarket, Kalshi, PredictIt, Manifold Markets, ESPN, The Odds API, NOAA, NHC, USGS, FRED, GDELT, FiveThirtyEight, Congress.gov, OpenFDA, Sleeper, Eurovision, Spotify Charts, TMDB, Google Trends, CourtListener, DOJ, Federal Register, Finnhub, and more.

Quick start (Python)

import requests

headers = {
    "X-RapidAPI-Key": "YOUR_KEY",
    "X-RapidAPI-Host": "sirius-prediction-market-api.p.rapidapi.com"
}

# Get trading signals
signals = requests.get(
    "https://sirius-prediction-market-api.p.rapidapi.com/v1/signals",
    headers=headers
).json()

print(f"Found {signals['data']['count']} signals")
print(f"Total stored: {signals['data']['total_stored']}")

for s in signals["data"]["signals"][:5]:
    print(f"  {s['side']} {s['market'][:50]} — gap: {s['gap_pct']}%")

Quick start (JavaScript)

const response = await fetch(
  "https://sirius-prediction-market-api.p.rapidapi.com/v1/signals",
  {
    headers: {
      "X-RapidAPI-Key": "YOUR_KEY",
      "X-RapidAPI-Host": "sirius-prediction-market-api.p.rapidapi.com"
    }
  }
);
const { data } = await response.json();
console.log(`${data.count} signals from ${data.sources_active} sources`);

Endpoints

Endpoint	Description	Tier
GET /v1/markets	All active markets + odds	Free
GET /v1/signals	Trading signals from 28+ sources	Free (15min delay)
GET /v1/signals/history	Historical signals + results	Free
GET /v1/sentiment	Fear & Greed, long/short ratios	Free
GET /v1/sports	Live sports odds	Free
GET /v1/weather	Weather forecasts	Free
GET /v1/odds	Cross-platform odds comparison	Free
GET /v1/performance	Bot track record & win rate	Basic
GET /v1/trades	Trade history with P&L	Basic
GET /v1/brain	AI reasoning engine	Pro

Signal Detection Layers

The API exposes signals from 6 algorithmic detection layers that scan continuously:

L1 — Price Lag: Black-Scholes model vs Polymarket odds on crypto markets
L3 — Weather: NOAA/NHC/USGS data matched to weather prediction markets
L4 — Kalshi: Cross-platform arbitrage between Kalshi and Polymarket
L5 — Sports & Politics: ESPN live scores + Kalshi political predictions
L6 — Universal: 20+ sources including PredictIt, Manifold, Odds API, FRED, GDELT, Google Trends, and more