I am brand new to trading, but I am interested in building an automated trading system in Java, and I've seen that certain brokers have APIs. I am looking for the simplest, but mostly the cheapest system that has a Java API, including broker + API. A manual interface is not needed, although I guess it could be useful occasionally. Are brokers strictly necessary for easy trading? I've looked at several brokers and they seem to be full of non-transparent fees, and I need almost none of what they provide (I don't need their data, advisors, etc.; a visual summary of gains, losses, etc. might be nice but not necessary). Thank you for your help!