Robinhood - Free stock trading service.
Stonksfolio - Gain insight into the performance of stock & ETF investments
TradeStation - Whether you trade stocks, ETFs, options or futures, TradeStation’s award-winning tools and...
Bux - Casual stock trading - thumb swipes only
OptionsHouse - OptionsHouse is an online stock trading platform with an easy-to-use interface.
Contora - Alternative data on the companies activity on the web for retail traders