Senior Full Stack Engineer (.NET / React)

Senior Full Stack Engineer (.NET / React) Warsaw, hybrid, 3 days per week from the office. Responsibilities Build and enhance frontend applications and backend services supporting treasury workflows. Develop React/TypeScript single‑page applications and reusable UI components. Design and implement ASP.NET Core REST APIs with scalable pagination and filtering models. Optimize performance across the stack, including APIs, serialization, rendering, and large data grids. Collaborate with business stakeholders, quant teams, and product managers to deliver user‑focused solutions. Drive engineering best practices including code reviews, testing, CI/CD, and production support. Investigate production issues and improve observability and platform reliability. Mentor engineers and contribute to technical growth within the Warsaw team. Requirements 5+ years of software engineering experience building production systems. Strong experience with C#/.NET ecosystem and ASP.NET Core . Strong frontend experience with React and TypeScript. Experience building REST APIs and handling large datasets efficiently. Hands‑on experience with ag‑Grid, Highcharts, or similar UI/data visualization libraries. Strong understanding of authentication, authorization, and serialization mechanisms. Experience working with relational databases and performance optimization. Strong communication skills and ability to work directly with business stakeholders. Nice to Have Experience in treasury, trading, or financial systems. Strong product mindset and UX awareness.