Currently, for equities, Alpaca Securities LLC supports the trading of listed U.S. stocks and certain over-the-counter ADRs.  Furthermore, Alpaca Crypto supports a number of cryptocurrency coins.  You can find out which coins Alpaca supports by clicking this link.

alpacahq/Alpaca-API
The Alpaca API is a developer interface for trading operations and market data reception through the Alpaca platform. - alpacahq/Alpaca-API