Well, XKCD seemed to use Wolfram Alpha when Mathematica fell over: https://what-if.xkcd.com/62/ https://what-if.xkcd.com/62/ > While researching this article,

Well, XKCD seemed to use Wolfram Alpha when Mathematica fell over: https://what-if.xkcd.com/62/ https://what-if.xkcd.com/62/ > While researching this article, I managed to lock up my copy of Mathematica several times on balloon-related differential equations, and subsequently got my IP address banned from Wolfram|Alpha for making too many requests.