Avalonia UI

Why this conversation

An application that has to run on Windows, Linux and macOS usually means several code bases, several teams, and the same feature tested again on each. The host stopped at the Avalonia UI booth at Techorama Netherlands 2026 in Utrecht on 27 October 2026 and asked Max Katz what they are doing there. His answer was one UI, one code base and one language, and an argument for why that matters more now that AI agents write code too.

One UI for desktop and mobile

“We develop a desktop and mobile framework for the developers”, Max said, so that you can have a single pixel-perfect UI “and reduce your headache when you write and test it”. Write it on Windows and you can be sure that Linux and macOS will work exactly as well and look the same, if that is what you want.

If it is not, you can define different styles for different platforms. There are integrations for each platform, so an application can use features specific to Linux or macOS while everything stays in a single code base, developed in a single language. That reduces the need for several developers with different backgrounds.

One code base for AI agents

Max added a reason that belongs to the present: “in the modern age of AI, it’s also way easier to have an agent to work on a single codebase, improve it, test it once with your unit tests or maybe end-to-end UI tests”.

Getting started

Avalonia is an open-source framework. It is on GitHub, with documentation and a website with quick-start guides. For a first, simple application you would typically start from the Avalonia templates, which are available from NuGet, “as typically goes with .NET applications, .NET templates”. “So you install Avalonia templates”, run the application, “and your application is running. And then you can go ahead and write your awesome apps.”

The roadmap

“We are now working on expanding our ecosystem”: more tooling, better IDE integration and some experimental products. “And also, we are working on new controls.” Avalonia itself is free and open source; the company sells some additional controls for more advanced use cases, “for example, PDF viewer or, let’s say, rich text editing”. Around them is a large ecosystem of third-party controls, which anyone can extend, or add their own to share.

.NET first, and complex UIs

Does it support other programming languages? “We focus on .NET”, Max said. Some projects and tools reach into other ecosystems, but it is primarily .NET.

Its targets are business applications with complex UIs. Asked whether rendering can be optimised for parts of the screen that refresh independently, he answered: “Of course.” Avalonia is primarily optimised for desktop, where applications have very complex trees. It can be used on mobile too, where the UI will most likely be much simpler, built around scrolling.

Where to start

The main website is avaloniaui.net, and the documentation is at docs.avaloniaui.net. The host closed by proposing to build the software of tomorrow in Avalonia.

When it comes out

The episode is edited and in the release order. Like every episode it goes out on YouTube first, then on Apple Podcasts, Spotify and Amazon Music.