Discovering UNO Platform: My First Steps

📌 About Me & UNO
I first discovered UNO Platform when I joined Nventive. My initial role involved manual testing of cross-platform mobile apps, which quickly introduced me to UNO’s unique approach. That experience gave me the chance to meet the UNO Platform team and witness firsthand how this framework was opening new doors in app development.

Starting at nventive has been full of surprises, and one of the most exciting has been discovering UNO Platform. My first exposure wasn’t through writing code but through manual testing of cross-platform mobile apps. Even from testing, I noticed something different: the same app running smoothly on Android, iOS, and Windows — all from one codebase. That simple fact made me realize this framework had something unique.

Soon after, I had the chance to meet the UNO Platform team. Their passion and vision immediately stood out. They weren’t just solving a technical challenge; they were building a bridge that could truly change the way developers create apps across platforms.

What is UNO Platform?

At its core, UNO Platform is an open-source framework that lets developers build apps in C# and XAML and run them everywhere:

• Windows
• iOS
• Android
• macOS
• Linux
• WebAssembly (right in the browser)

The promise is simple yet powerful: write your app once and run it everywhere.

UNO builds on Microsoft’s WinUI framework, extending it to non-Windows platforms. This means that when I write a button in XAML, the same code will display as a native button on each platform. The result is an app that feels natural on every device, without requiring developers to rewrite code for each environment.

A Young but Promising History

UNO Platform is still a very young project. The first version was released on May 7, 2018, under the Apache 2.0 license. From the beginning, it was described as a UWP bridge — allowing developers to reuse Universal Windows Platform code on iOS, Android, and WebAssembly.

UNO has already proven that it can deliver real apps across multiple platforms, while keeping a single, consistent codebase in C# and XAML.

How UNO Platform Works

UNO relies on a combination of technologies that make cross-platform development possible:

• On iOS and Android, it builds on Xamarin, tapping into each platform’s native frameworks.

• On the Web: it runs on Mono WASM, a runtime that executes on WebAssembly.

WebAssembly itself is worth a quick detour. Think of it as a binary format for the web — designed to run at near-native speed in the browser. It allows higher-level languages like C++ or C# to be compiled and executed in a browser environment, which traditionally has been dominated by JavaScript.

This combination is what makes UNO different: it’s the only platform currently available that can deliver apps to mobile, desktop, and the web using C# and XAML from a single codebase.

Debugging in WebAssembly

Because WebAssembly is still evolving, debugging support is also developing rapidly. With UNO Platform, I can already debug C# code running in the browser, which is something that felt almost impossible not long ago. The experience keeps improving, and it’s exciting to see how quickly the tooling is advancing to make the developer workflow smoother.

Why UNO Platform Feels Different

I know there are plenty of frameworks promising cross-platform solutions. But what makes UNO stand out to me is that it doesn’t feel like a compromise. It delivers apps that look and feel native on every platform, while keeping development efficient with one shared codebase.

From my very first days testing apps, I’ve felt the impact of this approach. It’s not just about reducing duplicated work — it’s about empowering developers to bring ideas to life across devices, without being held back by platform boundaries.

Call to Action

UNO Platform is growing fast, and I’m just starting my journey with it. If you’re curious about building cross-platform apps with C# and XAML, I encourage you to check it out for yourself. You can learn more at platform.uno and explore the source code on GitHub.

This is only the start — I’ll be sharing more about new features, releases, and my experiences as I continue learning and testing with UNO. Stay tuned!