Polygon API

Finance / API Key Intermediate HTTPS
5 calls/minute (free tier)

Overview

Polygon.io is a comprehensive market data API providing real-time and historical stock, forex, and cryptocurrency data. You can retrieve OHLCV price bars, live quotes, trade data, and company fundamentals for thousands of tickers. It is a popular choice for developers building trading algorithms, financial dashboards, and quantitative research tools.

💡

Beginner Tip

The free tier provides access to previous-day data with a 15-minute delay; upgrade to a paid plan for real-time streaming or intraday data if your app requires live prices.

Available Data

Symbol
Results count
Date
exchange rate between currencies
conversion result
supported currency list

Example Response

JSON Response
{
  "base": "USD",
  "date": "2025-01-15",
  "rates": {
    "EUR": 0.92,
    "GBP": 0.79,
    "JPY": 149.5,
    "CAD": 1.35
  }
}

Field Reference

ticker The stock ticker symbol for the requested security.
results Array of OHLCV bar objects for the requested time range.
o Opening price of the security for the given time interval.
h Highest price reached during the time interval.
c Closing price of the security at the end of the time interval.
v Total trading volume (number of shares) during the time interval.

Implementation Example

// Get daily stock aggregates (OHLCV)
const url = "https://api.polygon.io/v2/aggs/ticker/AAPL/range/1/day/2023-01-09/2023-01-10?apiKey=YOUR_API_KEY";

const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();

console.log(`Symbol: ${data.ticker}`);
console.log(`Results count: ${data.resultsCount}`);
data.results.forEach(bar => {
  console.log(`Date: ${new Date(bar.t)}, Open: $${bar.o}, High: $${bar.h}, Low: $${bar.l}, Close: $${bar.c}, Volume: ${bar.v}`);
});

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

403 Forbidden Your API key does not have access to the requested endpoint or data tier
Check which endpoints are included in your Polygon plan; some data like real-time quotes require a paid subscription.
404 Not Found The ticker symbol does not exist or is formatted incorrectly
Use uppercase ticker symbols (e.g., AAPL not aapl) and verify the ticker is traded on a supported exchange.
429 Too Many Requests API request rate limit exceeded for your subscription tier
Implement request throttling and use the Retry-After header value to determine when to retry requests.

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 5/20
🔒 Security 15/15
🛠 Developer XP 12/20
✓ Reliability 10/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Finance
Difficulty Intermediate
Verified: 2026-04-07

Alternatives to Polygon

Technical alternatives for different use cases.

Real-time and historical market data with WebSocket

Better For

Free tier availability and pricing

Trade-off

Institutional-grade market data with low latency

Similar APIs

View All →