For use in Windows, this Java library interfaces with the Bloomberg API. The Bloomberg API provides free, unrestricted access to raw financial data on current market trades (either real-time or delayed), reference data on historical information, and records of intraday trading. As part of their Open Market Data Initiative the library is offered under a "free-use" license, which allows unrestricted access to the interface's header files, documentation, and programming examples. Extensive documentation, including code examples, is available in the Developer Documentation and at the API website.
Should you let people scrape data from your site or offer a web service API instead? This is one of the classic arguments for offering an API: to get better control over how your data is accessed and who gets access. A recent news story about Flybe, Europe's largest independent regional airline carrier, demonstrates a case where this was the main driver for creating an API. For Flybe, having third party service and applications access their booking engine is very important to them, but they want to make it more structured and reliable.
DriveWealth has announced an expansion of its API portfolio. The latest set of APIs focus on wealth management and assist investment advisors to better serve their clients. The new APIs enable recommendations, automated portfolio balancing, and fully discretionary investor options.