I find OpenQuant to be an excellent Automated Trading System (ATS) development and execution platform. Very clean, comprehensive, and well thought out class and event architecture. The online help file is somewhat weak; however there is a good Getting Started guide and lots of sample code to get you going. Reasonable support forum assistance. However, OpenQuant does not lend itself well to rapid interactive exploration and experimentation. For that I use Amibroker. I use Amibroker as my discovery tool, kind of like Excel, to test tens of ideas, and to run thousands of backtests (AmiBroker backtest is roughly 150 times faster than OpenQuant, and 1 to 2 orders of magnitude faster than any other tool I have tested). Good documentation, large user base, and fanatical customer loyalty (== good support forum assistance). After I create and refine a trading strategy with AmiBroker, I use OpenQuant as my development platform, for easily and rapidly developing and deploying robust unattended automated trading code. After many years of trying out almost every platform and tool out there, and writing my own custom Automated Trading Systems applications (first in C++, then C#), I settled on this combination. It works well for me. My copy of OpenQuant currently trades 11 automated & unattended (except for a morning restart) strategies in live mode with real money. So far I am generating a decent return (which makes me happy). I am posting this message as an extremely satisfied customer of both OpenQuant and Amibroker. I have no relationship with either company (other than having paid for their software). I hope this might save people who are building Automated Trading Systems some time in their search for software tools.