Senior Full-Stack Engineer Java + React 4-6 years of experience. Only Poland-based candidates

We are a U.S.-based fintech startup operating in the investment and financial services space. Our distributed teams work across Poland, the United States, and Ireland, collaborating on technology-driven solutions related to stocks and investments.

Security, compliance, and the responsible handling of sensitive financial data are central to how we operate, as we build scalable products in a regulated environment.

Responsibilities

- Modernize legacy systems via redesign and refactoring.
- Develop UI using React + Nexus design system.
- Build APIs with proper security and lifecycle governance. - Design reusable component libraries and UI frameworks. - Collaborate with UX, product, and architecture teams. - Optimize frontend and backend performance.

- Support public API documentation and governance.

Skills

- Strong Java + Spring Boot backend capability.
- Expertise in React, TypeScript, Nexus UI components.
- Experience with modernization and migration projects.
- Understanding of microservice and API design.
- Familiarity with CI/CD, linting, testing frameworks.
- Knowledge of frontend security and performance patterns. - Good collaboration across UX and backend teams.