For our client – an international technology company building high-performance trading systems used by professional market participants – we are looking for a Senior .NET WinForms Developer to join the frontend engineering team responsible for real-time desktop applications.

This role focuses on building fast, responsive, custom-rendered desktop UI components. It is not about configuring ready-made UI libraries, but about creating efficient solutions from the ground up.

Key responsibilities

Design, implement and optimize custom WinForms controls (charts, grids, interactive visualization components)
Build and maintain high-performance desktop applications handling continuous real-time data streams
Ensure smooth multi-threaded UI updates without blocking or freezing the interface
Collaborate with backend engineers (C++ systems) to maintain low-latency TCP/socket communication
Profile, debug and optimize rendering performance (GC pressure, paint cost, batching, flicker control)
Contribute to improving engineering standards, UI architecture, and usability

Ideal candidate profile

5+ years of experience developing desktop applications in C#/.NET (preferably .NET 8)
Strong hands-on experience with Windows Forms
Proven experience building custom UI controls from scratch (custom rendering, inheriting from base controls – not only configuring UI libraries like DevExpress/Telerik/Infragistics)
Experience working with continuous real-time data streams pushed directly to the UI
Strong understanding of multi-threaded UI applications and safe UI updates from worker threads
Practical experience in UI performance optimization (minimizing redraw cost, GC pressure, flicker prevention, batching updates)
Experience working with TCP / socket-based communication
Ability to explain previous technical decisions and UI trade-offs
English level: min. B2+

Nice to have

Experience with trading systems or real-time financial applications
Familiarity with C++ or C# interoperability with native components
Understanding of high-performance data visualization patterns

Conditions

Work model: Remote
Contract type: B2B
Rate: 125–140 PLN/h + VAT

Recruitment steps

Phone call with Recruiter
Technical interview with Client (may required 2 rounds)
Feedback and decision

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Senior .NET WinForms Developer

KUBO Poland