Bubble vs ProtoPie: Which is best for you?

They use a Work Unit structure to charge and you can be surprised. With that said, the tiers availabel are easy to manage and you can place limits to keep expenses in check.

I deleted my payment details to close my account and was continually billed after this, despite not using the service and customer service say they can not refund me.

It is double the price of Adobe CC, but with Adobe CC one gets over 20 other pieces of industry-leading creative software. With this said, this is a niche area and ProtoPie, in my view, is at the top in terms of providing a tool that gives one the ability to present high-end demos and more robust testing (outside of actual coding).

Several basic aspects of functionality are missing or require goofy workarounds, such as being able to distinguish between single and double clicks or detecting the intersection/overlap of objects.