Full-Stack Developer for Web & Mobile Product - Eastern Europe Only

We are looking for an experienced full-stack developer to support an established web and mobile product. The work includes developing and improving features, debugging existing functionality, working with third-party APIs, and supporting cloud-based services. The product includes web and mobile workflows, external integrations, data-driven features, and some AI/LLM-powered functionality. Experience integrating AI APIs or working with LLM-based features is a plus. You should be comfortable working across frontend and backend code, REST APIs, SQL databases, and existing application logic. AWS experience is strongly preferred, particularly experience troubleshooting applications and services running in a production cloud environment. A strong QA mindset is important. You should test your own work carefully and be comfortable reproducing bugs, checking edge cases, validating API and database behavior, regression testing, and verifying fixes before considering a task complete. Previous hands-on QA or software testing experience is a strong advantage. Experience working with complex or data-sensitive applications is preferred. Previous experience with FinTech, payments, banking, accounting, insurance, or similar systems is a plus, but not required. This is an existing application rather than a greenfield build. You should be comfortable understanding unfamiliar code, investigating existing behavior, fixing bugs, and adding features without unnecessarily rewriting working parts of the system. We are looking for someone dependable who can work independently, communicate clearly with a distributed team, and maintain consistent availability during agreed US business hours. Requirements: - Currently based in Eastern Europe - Strong full-stack web development experience - REST API and third-party integration experience - SQL/database experience - AWS/cloud experience - Strong debugging and problem-solving skills - Good QA/testing mindset - Clear written and spoken English - Reliable availability during agreed US business hours Nice to have: - FinTech or other financial software experience - Mobile application experience - AI/LLM integration experience - Manual or automated QA experience - Experience maintaining large existing production applications When applying, please include your current location, recent full-stack development experience, AWS experience, QA/testing experience, any FinTech or financial-software experience, and your normal working hours. Important: Please do not apply if you are not currently based in Eastern Europe.