Alpaca Trading API - Simple REST API for commission-free stock trading
Robinhood - Free stock trading service.
TradeStation - Whether you trade stocks, ETFs, options or futures, TradeStation’s award-winning tools and...
Alpaca Data API - Free real-time stock market data API
OptionsHouse - OptionsHouse is an online stock trading platform with an easy-to-use interface.
Alpaca Fractional Trading API - Commission-free API to trade & invest for as little as $1