Partly deceptive about free, not very stable

I am disapointed. This app presents a general instability that makes it difficult to use. It loads the PDF fine, then crashes at random.

Another rather surprising thing is that it’s free alright, but after conversion (when it does not crash), it displays a dialog that has a big green button ‘Upgrade now’, but it displays an outside page where one has to pay with a credit card and get delivery not from Apple but from some unknown source. Would it not be much more proper to have the option to buy inside the app, along Apple guidelines ?

MitchBook about Any Free PDF to JPG Converter