The IEX API is a is a free, web-based API supplying IEX quoting and trading data.

The IEX API is a set of services designed for developers and engineers. It can be used to build high-quality apps and services.

“Data provided for free by IEX. View IEX’s Terms of Use.”

https://iextrading.com/api-exhibit-a/
https://iextrading.com/api-terms/