Depending on the quality of data / amount of history / markets you need there are several options. Industry standard in prop firms is CQG, but I have seen people using eSignal ( or futures workstation), Reuters, Bloomberg and others (DTN, Barchart) Hope this helps
Barchart: http://www.barchart.com/interactive_charts/futures/CLZ15 Then click the spreads tab and enter the fly like a formula into the box, like below: CLX15-(2*CLZ15)+CLF16 That should do the trick.