# Massive API (formerly Polygon.io)

Category: [Finance](https://free-web-services.com/web-services/unit-convertors/fiinance/)  
Page: https://free-web-services.com/web-services/unit-convertors/fiinance/massive-api.html  
Documentation: https://massive.com/docs/rest/quickstart

The Massive API, formerly Polygon.io, gives stock, options, forex and crypto market data, for example the previous day's prices for a share. Requests are GET calls with an apiKey parameter or a Bearer header, and the answers are JSON. Free with a free API key for 5 requests a minute. An official MCP server (github.com/massive-com/mcp_massive) lets AI agents read the market data.

- API key: Needed, free
- Pricing: Free with a free API key for 5 requests a minute.
- From the browser: Yes (CORS)
- Formats: JSON
- Interface: REST, HTTP-GET, MCP
- Provider: massive.com

Example request:

```sh
curl 'https://api.massive.com/v2/aggs/ticker/AAPL/prev?apiKey=YOUR_API_KEY'
```

Replace YOUR_API_KEY with your own key. The JavaScript works in a web page as well as in Node.js 18 or newer.