"Built using XamarinForms from the ground up, the app was initially created to create a niche but useful, API-driven app for iOS and Android platforms for UK company information lookup. FastUKCompanySearch allows UK-based companies registered with Companies House, the official company register, to be looked up, along with company financials, director information, filing history, and annual returns. The app was built over a year, in the developer's spare time as a hobby. The main reason for picking Xamarin was to allow for rapid development for iOS and Android without having to rewrite the same app twice, once using Java/Kotlin and then again in Objective-C/Swift. XamarinForms was picked to further speed up development by allowing XAML to be used for the GUI. By far the biggest challenge was XamarinForms itself. While it is a truly remarkable product, the builds were often unreliable. Strange errors regularly popped up often requiring a regular "Delete bin/obj folders, clean the solution, and restart Visual Studio" cycle. The situation has vastly improved since XamarinForms 4.x however. The lack of a stable XAML GUI designer was yet another challenge as the WYSIWYG designer in Visual Studio has proven nearly unusable. For a period LiveXAML was used to update the UI and now with VS2019's Hot reload feature, making GUI changes and seeing them reflected on screen immediately is a God send. Since its launch, the app has attracted a respectably sized user base ( considering this is for a niche market). Combined monthly searches exceed 10K across the platforms and the app has a 4.5-star rating on both iOS and Play Store. Working with XamarinForms, despite the unreliable build tools, has been an enjoyable experience. The amount of time saved by writing once and being able to deploy to both iOS and Android is significant and makes it easy for any .Net developer to hit the ground running. The app is updated monthly, and allowing users to download business credit reports is one of the main items on the roadmap."