Massive (Polygon.io) API: Market Data Guide for Traders

Q: Do I need a new API key after the rebrand?

No. Existing Polygon keys work against both api.polygon.io and api.massive.com.

Quick answer

Massive, formerly Polygon.io (renamed October 30, 2025), serves US stocks, options, indices, forex, crypto and, since 2026, US futures through REST, WebSocket and flat files. One aggregates endpoint returns bars of any size; old Polygon keys and api.polygon.io still work alongside api.massive.com. The free plan allows 5 calls per minute with end-of-day data and two years of history.

Massive (Polygon.io) API at a glance

Pricing: Free: 5 calls/min, end-of-day, 2 years
Availability: Worldwide
Paper trading: Not applicable (data only)
Integration type: REST + API key
In AlgoGP: Built in: data adapter (Pro)
REST base: https://api.massive.com (api.polygon.io still served)
Auth: apiKey query parameter or Authorization: Bearer <key>
Bars: /v2/aggs/ticker/{ticker}/range/{n}/{timespan}/{from}/{to}
Free plan: 5 calls per minute, end-of-day data, 2 years of history

The aggregates (bars) endpoint

One endpoint returns bars of any size: /v2/aggs/ticker/AAPL/range/1/day/2024-01-01/2025-01-01?adjusted=true&sort=asc&limit=50000. timespan is minute, hour, day, week or month, and the multiplier builds sizes like 4-hour (range/4/hour). Results are {t, o, h, l, c, v, vw, n} with t in Unix milliseconds.

Asset	Ticker format
US stocks / ETFs	`AAPL`, `SPY`
Crypto	`X:BTCUSD`
Forex	`C:EURUSD`
Indices	`I:SPX`
Options	`O:SPY251219C00600000`

Free vs paid plans

The free Basic plan allows 5 requests per minute with end-of-day data and two years of history: enough for a daily backtest on a few symbols. Paid plans per asset class remove the rate limit and add minute bars, longer history, real-time or 15-minute-delayed data and WebSocket streams; Stocks Starter, for example, is $29/month with unlimited calls and five years of history. In 2026 Massive also added US futures (CME-family contracts such as ES, GC and CL).

Use Massive (Polygon.io) in AlgoGP

Open a project, go to the APIs & keys tab and, under Platforms, pick Massive (Polygon.io) as the market data source (market_data.py). The choice is saved to config.json as a new strategy version:

{
  "platforms": {
    "data": "polygon",
    "broker": "alpaca"
  }
}

In-app backtests always use AlgoGP’s normalized history so results stay comparable; this choice decides what backtest.py and live.py connect to when you run the exported code.

Key	What it is
`POLYGON_API_KEY`	Massive (formerly Polygon.io) API key from the dashboard; old Polygon keys still work.

Names the generated code reads. Add values under Keys & secrets or in a local .env.

New to Massive (Polygon.io)? Follow the step-by-step Massive (Polygon.io) API key guide.

Massive (Polygon.io) API: frequently asked questions

Is Polygon.io the same as Massive?

Yes. Polygon.io renamed itself Massive on October 30, 2025. Accounts, keys, pricing and APIs carried over; polygon.io links redirect to massive.com.

Do I need a new API key after the rebrand?

No. Existing Polygon keys work against both api.polygon.io and api.massive.com.

Is there a free Polygon/Massive plan?

Yes: 5 API calls per minute, end-of-day data and two years of history for stocks, with similar free tiers for other asset classes.

Turn Massive (Polygon.io) data into a tested strategy

Backtest an idea in the browser, then export Python whose live loop reads candles straight from Massive (Polygon.io) with your own key.

Generated Massive (Polygon.io) candle fetcher, closed bars only
An AI copilot that writes and revises the rules
Pair it with Alpaca, Binance, OANDA or another broker

Build with Massive (Polygon.io) data Compare platforms

Free plan, no card required. Massive (Polygon.io) is included with Pro.

Massive (Polygon.io) alternatives

Comparisons

Independent guide. AlgoGP is not affiliated with Massive (Polygon.io). Limits, prices and availability change; confirm them in the official documentation. Nothing here is investment advice.