Mobile App Dev of Beta version

We are wanting to build a Beta version of a mobile application, in IOS and possibly Android and Windows (but not essential for the Beta version). Once we have the Beta version developed, we will seek investment and hire developers. At this stage, we are limited with development knowledge.

I have looked at online tools and find a) simple tools that build pages and have no data capability b) simple tools that have only data capabilities and too limited design flexibility or c) very complex tools that require advanced knowledge beyond what we have now.

So, my question is: does anyone know an online mobile app dev tool where we can build a custom designed application that will all house data?