Ideine 

Write your app using System.Net.Http, but drop this library in and it will go drastically faster. Use Okhttp3 instead of Okhttp

ZXing.Net.Mobile is a C#/.NET library based on the open source Barcode Library: ZXing (Zebra Crossing), using the ZXing.Net Port. It works with Xamarin.iOS, Xamarin.Android, Windows Phone (Silverlight) and Windows Universal. The goal of ZXing.Net.Mobile is to make scanning barcodes as effortless and... More information