The backtesting tool that is available on TradingView.com (it's also available on the infinitely inferior Barchart.com)
Do you know the one I am talking about Charlotte?
It lets people test a strategy without needing to know how to program. Sometimes trades are too complex to be done entirely programmatically anyway (a few basic parameters can alert you to a potential setup, then you can review it manually before deciding to go in)
TradingView.com is just generally more aesthetic, faster, responsive and intuitive.