Hybrid Full-Stack Engineer (React + .NET)

SINGU; Kraków; Hybrid; PLN 180,000 - 240,000; Full time

Job summary

SINGU is hiring a Full Stack Developer to join the QRmaint team. You’ll build a mobile-first CMMS with a focus on React and a solid grounding in C#/.NET, delivering features end-to-end from API to UI. Expect ~80% frontend and ~20% backend work as you rewrite the frontend in React.

You’ll collaborate with a cross-functional team, participate in code reviews, testing, and AI-assisted development, and contribute to a high-quality software product used by hundreds of organizations.

Qualifications

• 3+ years of commercial React development with strong TypeScript.
• Working C# knowledge: you can work in an existing codebase, ship smaller backend changes and grow from there.
• Proven experience integrating and designing REST APIs.
• Working knowledge of PostgreSQL.
• A genuine testing habit: unit and integration tests as standard practice.
• Comfort participating in code reviews and giving direct, useful feedback.
• Ownership of delivered features, from technical design to production and support.
• Practical experience with AI-assisted development tools, and the judgment to critically assess what they produce.
• Communicative English (B2+): technical specs, tickets, documentation.
• Communicative Polish (B2+): the team works in Polish internally

Responsibilities

• Frontend Development: Build interfaces in React and TypeScript as a core contributor to our frontend rewrite.
• Turn designs into responsive, accessible and performant UI, built on maintainable code.
• Contribute to shared components and our design system.
• Backend Development: Build and extend backend features in .NET 10 and C# 14.
• Design and develop REST APIs that are consistent, secure and well documented.
• Work with PostgreSQL database structures and help optimize queries, indexes and performance.
• Quality & Testing: Treat unit, integration and end-to-end testing as a core part of development, not an afterthought.
• Participate in code reviews with clear, constructive feedback.
• Write clean, secure, maintainable code aligned with our standards and best practices.
• AI-Assisted Development: Use AI tools (Cursor, Claude Code or similar) to accelerate development, code analysis and refactoring.
• Evaluate the correctness, quality, security and performance of AI-generated code before it ships.
• Delivery & Collaboration: Take part in product discovery and feature specification, as well as technical breakdown and estimation before development starts.
• Work within GitHub and CI/CD to deliver features reliably and on time, and own them through to production.
• Collaborate closely with the Team Lead, PM and Designer day to day and actively participate in Agile ceremonies
• Share knowledge and support your teammates

Skills

React

TypeScript

C# / .NET

REST APIs

PostgreSQL

Testing

Code reviews

AI-assisted

English (B2+)

Polish (B2+)

Tools

GitHub

CI/CD

AWS

Docker

Job description

SINGU is hiring a Full Stack Developer to join the QRmaint team. You’ll build a mobile-first CMMS with a focus on React and a solid grounding in C#/.NET, delivering features end-to-end from API to UI. Expect ~80% frontend and ~20% backend work as you rewrite the frontend in React.

You’ll collaborate with a cross-functional team, participate in code reviews, testing, and AI-assisted development, and contribute to a high-quality software product used by hundreds of organizations.