Trade with algorithms, connect to apps, and build services -- all using a commission-free stock trading API. Alpaca, a technology company located in the bay area of California, modularizes the world’s asset management activities. We are a diverse group of people with deep financial and technological expertise. Our investors include some of the most prominent figures in the industry. We are proud to be supported on various platforms by the love of passionate community members. Zero commissions to buy, sell, or short U.S. stocks. Both personal and business accounts are supported. Alpaca Securities LLC, a FINRA-registered broker/dealer, is designed for high volume trading. Paper trading allows you test the API and see how your strategies would perform. To run your strategies in live production, simply update the API endpoint.