Polygon.io

Polygon.io (now part of Massive) is a data platform modernizing access to real-time and historical financial market data. Developers, traders, researchers, and data scientists can tap into institutional-grade data directly from major exchanges using easy, fast, and reliable RESTful APIs, WebSockets, flat files, and SQL interfaces. The platform supports integration with popular AI tools and agents, enabling financial innovation, trading, and research solutions with accurate, low-latency data covering a wide array of asset classes.