Which brokers offer APIs that support fractional share trading?

Several brokerage platforms offer APIs that accommodate fractional share trading, providing flexibility and accessibility to investors and developers seeking to integrate trading capabilities into their applications. Here’s a detailed look at some of the notable brokers:
Interactive Brokers (IBKR): Interactive Brokers is renowned for its sophisticated API offering, which includes the ability to trade fractional shares. Their Trader Workstation (TWS) API supports multiple programming languages like Java, Python, and C++, making it a versatile option for developers. Interactive Brokers stands out with its extensive global market access and comprehensive suite of trading tools.
TD Ameritrade: TD Ameritrade’s API allows developers to build customized trading applications that can execute fractional share transactions. Their API is well-documented and provides features like price history, real-time quotes, and account-specific data. With the recent acquisition by Charles Schwab, users can expect continued enhancements in their API offerings.
Alpaca: Alpaca provides commission-free trading with APIs that support fractional share transactions. Their platform is designed with developers in mind, offering easy-to-use REST and WebSocket APIs. Alpaca targets algorithmic traders and investors by providing extensive documentation and a platform conducive to automated trading.
Fidelity: While Fidelity is better known for its traditional brokerage services, their API capabilities allow for fractional share trading through innovative features. Though it may not be as developer-centric as some competitors, Fidelity’s tools offer integration possibilities for advanced brokerage functionalities.
Robinhood: Known for popularizing commission-free trading, Robinhood also provides an API for fractional shares, although it is currently limited and not as freely accessible as those of other brokers. Robinhood’s focus is more retail-investor-focused, but they continue to expand their API capabilities with customer feedback.

For traders or developers interested in implementing fractional share trading in their applications, evaluating these brokers’ offerings could be beneficial, and it’s recommended to understand the specific functionalities and limitations of each platform’s API.