13 Python libraries for free market data everyone should know:
Theta Data
Real-time and historic, high-resolution, tick data for stocks and options. Theta Data is not free but there is a generous free tier and it's one of the cheapest sources of options data on the market.
Data for stocks (historic, intraday, fundamental), FX, crypto, and options. Uses Yahoo Finance so any data available through Yahoo is available through yfinance.