We are looking for an experienced .NET WinForms Developer to join the frontend engineering team and help build high-performance, real-time trading applications used by professional traders. 

This role is not about configuring UI frameworks - it is about crafting fast, responsive, custom-rendered desktop UI. 

IN SHORT:

🌎 100% remote or from the office (Wrocław, Bielsko-Biała) - You choose!

💰 125 - 140 PLN/h

☑️ B2B contract

💻 >5 years of commercial programming experience

Your Daily Missions 

  • Design, implement and optimize custom WinForms controls (charts, grids, interactive visualization components). 

  • Work with continuous real-time data streams and ensure ultra-responsive UI under load. 

  • Ensure smooth multi-threaded UI updates without blocking or freezing. 

  • Collaborate with backend engineers (C++ systems) to maintain low-latency TCP/socket communication. 

  • Profile, debug, and tune rendering performance (GC pressure, paint cost, batching, flicker control). 

  • Improve engineering practices, and influence UI architecture and usability. 

The Essentials We're Seeking 

  • 5+ years of hands-on experience developing desktop applications in C#/.NET (preferably .NET 8). 

  • Strong expertise in Windows Forms. 

  • Proven experience building custom UI controls from scratch (inheriting from base controls and implementing custom rendering - not configuring DevExpress/Telerik/Infragistics). 

  • Experience working with continuous real-time data streams, where data is pushed to the UI (not periodic refresh). 

  • Strong understanding of multi-threaded UI applications (updating UI safely from worker threads, avoiding freezes and stalls). 

  • Practical experience in UI performance optimization (reducing redraw cost, minimizing GC pressure, batching updates, preventing flicker). 

  • Experience working with TCP / socket-based communication. 

  • Ability to clearly explain previous UI design decisions, trade-offs, and the impact on end users. 

  • Fluency in English (minimum B2+). 

Nice to Have 

  • Experience with trading systems, market data, or real-time financial applications. 

  • Familiarity with C++ or interoperability between C# and native components. 

  • Understanding of high-performance visualization and data interaction patterns.