We have been building algo trading applications on many platforms, like Interactive Brokers, Ninja Trader, iQT, Omnesys Technologies with C# API, JAVA API, VB.NET API. We have implemented Options and Future parity based arbitrage strategy for a prop broker in India, We have also implemented different combination of technical indicators strategy on IB, which can place automatic orders, includes ability to start/stop/pause/resume/cancel individual sessions, ability to reconnect and resume sessions if connections is lost, logs for each trader, complete order management system, with order modification (for Limit orders), check open orders, cancel open orders (all based on certain rules) In a way, we understand the business and HFT, we have team who can build complete robust, customized system. Do let us know how to take it further and also we can arrange a demo of one of the project made on Interactive Brokers to display our credentials.