The ChartBuilder app in the App Store, Google play and Windows Store has recently been updated to version 2.0. This version addressed some critical issues and added pie chart support. With ChartBuilder you can build and customize a chart and then save it as a picture to your phone or tablet. We developed it using Xamarin.Forms and Xuni FlexChart and FlexGrid. In the future we plan to add data import, multiple axes, and possibly markers. Check it out and leave us a good review!