Senior Software Engineer

Join a global e-commerce technology organisation serving millions of customers across multiple international markets.

As a Senior Backend Engineer, you will become part of a team responsible for one of the company's most critical customer-facing domains. The platform supports customer subscriptions, plans, and purchasing journeys used daily by millions of users.

This is not a maintenance role. The team is actively transforming a mission-critical domain, modernising legacy systems, reducing technical debt, and building the next generation of scalable services that will support future growth.

You will play a key role in migrating core functionality from a monolithic architecture to modern microservices while helping shape the future architecture of a global platform.

What You'll Do

Build & Scale Core Services

• Design, develop, and maintain scalable backend services within a distributed microservices architecture.

• Build reliable systems supporting millions of customer interactions.

• Improve performance, reliability, and scalability across critical customer-facing services.

Drive Modernisation

• Lead the migration of key business domains from monolithic systems to modern microservices.

• Reduce technical debt and improve long-term maintainability.

• Design solutions that support future platform growth.

Shape Architecture

• Participate in architecture discussions and technical decision-making.

• Design orchestration layers supporting complex customer journeys and business processes.

• Help define engineering standards and best practices.

Work with Event-Driven Systems

• Build and operate services powered by event-driven architectures.

• Work extensively with Kafka and real-time lifecycle events.

• Design resilient and observable distributed systems.

Raise Engineering Standards

• Conduct code reviews and support other engineers through technical guidance.

• Promote best practices across software development, testing, deployment, and observability.

• Contribute to a strong culture of ownership and continuous improvement.

AI-Powered Engineering

• Use modern AI tools and coding agents throughout the software development lifecycle.

• Leverage AI for onboarding, architecture exploration, implementation, testing, debugging, and productivity improvements.

• Apply engineering judgement to validate, verify, and safely integrate AI-generated outputs.

What We're Looking For

Backend Engineering Expertise

• 5+ years of professional backend engineering experience.

• Strong experience designing and operating microservices architectures.

• Experience modernising legacy systems and decomposing monoliths.

• Solid understanding of distributed systems and scalable backend design.

Technical Stack

• Commercial experience with Go (Golang), Java, Kotlin or Scala

• Engineers coming from a JVM background should be open to working in a Go-driven environment.

• Hands-on experience with:

  • Kafka or similar event-streaming technologies

  • PostgreSQL

  • Docker

  • Kubernetes

  • CI/CD pipelines

Product & Ownership Mindset

• Comfortable owning solutions from idea through production.

• Strong problem-solving skills and ability to make technical trade-offs.

• Experience collaborating with product, business, and engineering stakeholders.

AI Fluency

• Practical experience using AI coding assistants such as Claude Code, Cursor, Copilot, or similar tools.

• Understanding of how context, prompts, constraints, and validation influence AI-generated outputs.

• Ability to critically review and verify AI-generated solutions.

Nice to Have

• Experience with subscription-based products.

• Experience in e-commerce environments.

• GraphQL knowledge.

• Familiarity with DDD, TDD, and BDD practices.

What We Offer

• Opportunity to build systems used by millions of customers globally.

• High-impact engineering work with significant architectural ownership.

• International collaboration across distributed engineering teams.

• End-to-end ownership from idea to production.

• Hybrid working model (3 days per week in the Warsaw office).

• B2B cooperation model.

• 30 days of paid annual leave.

• Modern office located in Warsaw city centre.

• Continuous learning and professional growth opportunities.