Middle/Senior .NET UI Developer (Avalonia/WPF, WebAssembly)

About The Project We are building a new industrial web platform designed to run both as an Azure-hosted SaaS solution and as an air-gapped on-premises installation from a shared codebase.

The platform uses modern .NET technologies, with Avalonia UI powering the user interface across browser-based WebAssembly and desktop applications.

You will help build the core UI framework, creating a reusable, modular, and high-performance interface for industrial dashboards and data-intensive applications.

The stack is .NET 10, ASP.NET Core, PostgreSQL/TimescaleDB, Keycloak, Docker and Kubernetes, with all UI in Avalonia.

We are looking for a Middle/Senior Frontend Developer with strong C#/.NET and Avalonia UI experience to build the user interface of a new industrial web platform running in the browser through WebAssembly and sharing code with desktop applications.

This is a UI-focused engineering role, not a traditional JavaScript frontend position. We are looking for someone experienced in building complex interfaces, reusable components, and UI architecture using Avalonia, or strong WPF/XAML expertise combined with hands-on Avalonia experience.

Requirements

• 5+ years of commercial experience with C# and .NET, including modern .NET versions.
• Production experience with Avalonia UI, or strong WPF/XAML experience combined with hands-on Avalonia development.
• Solid understanding of MVVM, dependency injection, and asynchronous programming.
• Experience building custom controls, styles, themes, and data-intensive interfaces such as grids, charts, and dashboards.
• Ability to write maintainable, testable code and collaborate through Git-based code review workflows.
• Availability to work remotely from within the EU and overlap with the US East Coast working hours from 08:00 to 13:00 ET.

Nice to have

• Experience migrating desktop applications from WPF or WinForms to Avalonia.
• Hands-on experience with Avalonia UI running in the browser through WebAssembly and understanding of its limitations.
• Familiarity with LiveCharts2, ScottPlot, OxyPlot, or commercial UI control libraries.
• Experience with plug-in systems or modular UI architectures.
• Unit testing of view models and automated testing practices.
• Knowledge of OIDC authentication, Keycloak, notifications, and file uploads.
• Experience optimizing WebAssembly applications through trimming, AOT compilation, or lazy loading.
• Familiarity with accessibility standards (WCAG) and localization.
• Experience building industrial, IIoT, manufacturing, or other data-intensive dashboard applications.
• Basic knowledge of ASP.NET Core and REST/OpenAPI.

Responsibilities

• Build the Avalonia UI shell: navigation, layouts, user preferences, and responsive and touch-friendly design.
• Create a reusable component library and themes (light, dark, high-contrast), with customer branding kept separate from themes.
• Implement UI extension points so plug-ins can add pages, dashboards and settings, with visibility driven by roles and licenses.
• Test and help select charting and control libraries for Avalonia WASM.
• Set up the localization architecture and port existing WPF screens to Avalonia.
• Optimize WASM load time and performance across the four target browsers.
• Write unit tests, take part in code reviews, and document UI decisions.