C# developer with Java or React

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.

4-6 years of experience is ok

Responsibilities

— Modernize legacy systems( C#) via redesign and refactoring.

— Build APIs with proper security and lifecycle governance.

— Collaborate with UX, product, and architecture teams.

— Optimize backend performance.

— Support public API documentation and governance.

Skills

— Strong ( C#) Jbackend capability.

— Experience with modernization and migration projects.

— Understanding of microservice and API design.

— Familiarity with CI/CD, linting, testing frameworks.

— Knowledge of security and performance patterns.

— Good collaboration across UX and backend teams.

In addition to this, if you have commercial experience with Java backend or React frontend — it will be a strong plus.

Recruitment steps:

• HR interview (30-45 min)
• Tehnical interview with live coding (40-45 min)
• Final client interview (30-45 min)
• Backround check
• Job Offer

The assignment is for between 26 to 32 months. You will work in a team of 9 engineers. The assignment is to migrate from monolith to microservices.

Important: the candidate must have worked/lived in Poland for the last 2+ years

Please read before applying:

The client is building a product in the bank/investment/brokerage systems niche, and their investors have strict security and compliance requirements, where every person will go through a background check.

What does this mean?

Before making an offer, they will check whether you have violated any EU laws.

For background check — you must be a taxpayer in Poland for 2+ years.