Robinhood - Free stock trading service.
TradeStation - Whether you trade stocks, ETFs, options or futures, TradeStation’s award-winning tools and...
Matador - Free investing + Social feed of trades + 2.5% on your cash
OptionsHouse - OptionsHouse is an online stock trading platform with an easy-to-use interface.
Qooore - Investing app for hypebeasts
Questrade - Questrade IQ Mobile is everything you need to trade stocks - right in the palm of your hand.