Robinhood - Free stock trading service.
Qooore - Investing app for hypebeasts
invstr - Investing for everyone (with fantasy $$$)
Matador - Free investing + Social feed of trades + 2.5% on your cash
M1 Finance - M1 helps you manage your money by automatically putting it to work in a customizable portfolio
Alpaca Trading API - Simple REST API for commission-free stock trading