Zeplin and Xamarin.Forms
Working in a small team with frequent design changes, the extension for Zeplin helps us quickly implement the design. It is also convenient due to its ability to generate a ResourceDictionary for Xamarin.Forms with all your colors and style.
Whether you are developing for web or creating mobile apps, Zeplin is a great tool that can boost your productivity by bridging the gap between design and code. Zeplin is a service available for free, but with one active project limitation.
Extensions
The several extensions it comes with, make it easy to translate design (exported from Sketch or Photoshop) into code. Extensions are offered for Swift, HTML, and others and as Zeplin has opened up for all developers, an extension for Xamarin.Forms was possible.
The Xamarin.Forms Zeplin extension was created to ease the development for Xamarin developers. It generates elements based on the design in Zeplin, then prints out XAML elements and CSS classes ready to be pasted into XAML pages or CSS file.
With Xamarin.Forms 3.0, CSS became another tool in the toolbox for Xamarin developers. While Xamarin.Forms support for CSS is not complete yet, most of what you would expect is there. You can still create apps the old way, however, if CSS is preferable to XAML styles it is worth exploring.
https://devblogs.microsoft.com/xamarin/xamarin-forms-and-zeplin-speed-up-your-design-to-development-process/