I’m creating a free back testing tool(long term)

I came across portfolio visualiser but it seems very complicated for a newbie and feels like submitting a tax filling.

I decided to build something simpler and more user friendly but having all the necessary tools for advanced investors.

What do you think about it?

What would you add or do different than portfolio visualizer?

Is there a feature you would love to have?

I’m open to all ideas. Thanks in Advance!