Our client is a top-tier proprietary trading firm building its own trading technology end-to-end. Their engineering teams develop high-performance Windows desktop applications relied upon by professional traders every day. As a Tech Lead, you will combine hands-on coding with architectural ownership to guide the evolution of real-time trading UIs. This role focuses on performance, responsiveness, and user experience at scale. IN SHORT:🌎 100% remote or from the office (Wrocław, Bielsko-Biała) - You choose!💰 150 - 190 PLN/h☑️ B2B contract💻 >8 years of commercial programming experienceYour Daily Missions Lead the architecture and development of real-time WinForms applications. Design and build custom-rendered controls for high-frequency, data-driven UI. Ensure ultra-responsive UI updates in a multi-threaded environment. Profile, debug, and optimize UI performance (latency, GC pressure, redraw behavior). Work closely with traders and C++ backend teams to deliver reliable, low-latency features. Mentor engineers through reviews, design sessions, and technical coaching. Work with source control and support transition plans (e.g., SVN to Git). The Essentials We're Seeking 8+ years of professional experience in C#/.NET with strong focus on Windows Forms. Proven ability to build custom UI controls from scratch (inheriting base controls and implementing custom rendering, not configuring DevExpress/Telerik). Hands-on experience with continuous real-time data streaming to the UI (data pushed, not polled or periodically refreshed). Deep understanding of multi-threaded UI architecture (safe UI updates from worker threads, no freezes or stalled redraw). Demonstrated skill in UI performance tuning (batching updates, reducing paint cost, minimizing flicker, lowering GC pressure). Experience working with TCP / socket communication and interacting with C++ backend systems. Ability to explain design decisions clearly and articulate the impact on end-user experience. Strong communication skills and experience mentoring or leading developers. Fluency in English (minimum C1) to collaborate effectively with stakeholders.  Nice to Have Experience with trading systems or real-time market data environments. Familiarity with C++ interop or mixed managed/unmanaged architectures. Comfort working with Figma or similar UI collaboration tools. Reasons Why You Would Enjoy Working With Us We work in the latest technologies and with international clients, and our projects are polished from < to /> - learn about some of the projects we have completed. We organize TechTalks, meet-ups and create guilds where we exchange knowledge - you can learn a lot from your teammates. We have a close-knit team and we make sure to have regular integrations - we often go out to celebrate together. You can work remotely or choose to work from our offices in Wroclaw or Bielsko-Biala. However, we count on your openness to occasionally visit the office for team meetings or client visits, or possible occasional trips to the client's headquarters. You can adjust your working hours to suit your needs, starting your day between 7:00 and 10:00 am. You can work with great specialists in their fields who also have a sense of humor and other after-hours hobbies. It is the people who create the unique atmosphere and relaxed atmosphere at CSHARK. We have a flat structure - we are not a corporation and don't want to be one 🙃. We offer bonuses for employee referrals (from 3000 PLN to 7000 PLN). We organize remote English classes and provide access to the company library. You can also become an author/author of articles published on our technical blog - https://cshark.com/blog/.