Senior Back-end Engineer

About the job Overview of the Role As a Senior Node.js Engineer in our Martech Tribe, you will design, develop, and optimize scalable backend services that power our marketing technology stack. Working primarily with Node.js, NestJS, and TypeScript within a microservices-based architecture, you will deliver high-quality, secure, and maintainable solutions that support internal applications used across multiple markets. The role requires strong technical ownership, sound architectural judgment, and close collaboration with Frontend, DevOps, QA, and Product teams. As a senior member of the team, you will also mentor others and contribute to raising the overall engineering bar. What You'll Do: Backend Development & Architecture Design and Develop Backend Services: Build robust backend services using Node.js, NestJS, and TypeScript, ensuring code quality, maintainability, and long-term scalability. Build and Maintain Microservices: Design, develop, and operate microservices-based architectures, while also supporting monolithic services where required, with clear boundaries, well-defined contracts, and resilient communication patterns. Design REST APIs and Service Communication: Design and implement RESTful APIs and internal service-to-service communication, applying sound API design principles, versioning strategies, and clear contracts for consumers. Contribute to Architectural Decisions: Actively participate in architectural discussions and technical solution design, helping shape the evolution of the tribe's backend systems and ensuring alignment with broader engineering guidelines. Integrate Third-Party Services: Integrate with external APIs and third-party platforms relevant to the Martech domain, handling authentication, rate limits, error handling, and data consistency reliably. Ensure Performance, Reliability & Security: Take ownership of the performance, scalability, reliability, and security of backend systems, applying best practices around authentication/authorization, data protection, and resilience. Cloud, Infrastructure & Delivery Work With AWS and Cloud-Native Services: Build and operate services on AWS infrastructure, leveraging cloud-native capabilities to deliver scalable, cost-effective, and resilient solutions. Develop Containerized Applications: Develop and maintain containerized applications using Docker and Kubernetes, ensuring consistent runtime behavior across environments and smooth deployment workflows. Contribute to CI/CD Pipelines: Contribute to CI/CD pipelines and deployment processes, ensuring changes are tested, automated, and shipped safely and predictably. Troubleshoot Production Issues: Investigate and resolve complex production issues, identify root causes, and drive long-term improvements to system performance, observability, and stability. Code Quality & Engineering Practices Write Clean, Maintainable Code: Produce well-structured, documented, and testable code that adheres to the team's coding standards and is easy for others to read, extend, and operate. Conduct Code Reviews: Conduct thorough, constructive code reviews and contribute to continuously improving engineering standards, patterns, and tooling within the team. Apply System Design Best Practices: Apply system design principles and best practices in everyday work, balancing simplicity, performance, and maintainability when proposing or implementing solutions. Champion Testing: Support a strong testing culture by writing appropriate unit, integration, and contract tests, and by helping ensure that backend services are well-covered and reliable. Collaboration, Mentoring & Communication Collaborate Across the Tribe: Work closely with Frontend, DevOps, QA, and Product teams to deliver features end-to-end, ensuring backend services meet real product and integration needs. Mentor Other Engineers: Mentor junior and middle engineers, share knowledge generously, and actively support the technical growth of the team through pairing, design discussions, and reviews. Articulate Technical Decisions: Communicate technical decisions clearly to both technical and non-technical stakeholders, explaining trade-offs and the reasoning behind chosen approaches. Drive Continuous Improvement: Bring a proactive mindset to identifying improvements in code, architecture, processes, and tooling, and help turn those ideas into concrete changes. Raise Issues Early: Communicate blockers, risks, or concerns proactively to the Team Lead and Scrum Master so the team can adapt quickly and keep delivery on track. What We're Looking For: 4+ years of experience in backend development with Node.js. Strong, hands-on experience with NestJS and TypeScript in production environments. Solid understanding of microservices architecture and distributed systems, including their typical challenges (consistency, observability, failure modes). Proven experience designing and implementing RESTful APIs. Solid knowledge of authentication and authorization mechanisms (JWT, OAuth, session-based auth, etc.). Experience working with relational and/or NoSQL databases, including data modeling, querying, and performance considerations. Understanding of event-driven architecture and experience with message brokers (e.g., Kafka, RabbitMQ, or similar). Hands-on experience with AWS services in a production setting. Strong experience with Docker and Kubernetes for building and operating containerized workloads. Understanding of CI/CD processes and experience integrating backend services into automated delivery pipelines. Familiarity with system design principles, best practices, and common architectural patterns. Strong analytical thinking and problem-solving skills, with the ability to break down complex problems into clear, manageable solutions. Ownership and accountability for assigned tasks, from design through to production. Strong communication skills and the ability to articulate technical decisions clearly. Mentoring mindset and willingness to support the growth of other engineers in the team. Proactive attitude and a continuous improvement mindset. Ability to collaborate effectively across teams in a hybrid work environment. English level: B2 or higher (written and spoken). Bonus Points For: Experience in Martech (marketing automation, CDPs, personalization platforms, analytics tooling, A/B testing, tag management, or similar). Experience building backend systems for internal tools and platforms used by multiple teams or markets. Experience with infrastructure-as-code (e.g., Terraform, CloudFormation). Experience with observability tooling (logging, metrics, tracing) and incident response. Experience with additional cloud platforms (Azure, GCP) or hybrid setups. Experience working in a Tribe-based organizational structure. About Flutter CEE We are Flutter Central & Eastern Europe (CEE). As a proud member of the Flutter family - a global leader in sports betting and iGaming - we are building one of the Group’s most dynamic tech and product hubs in Central and Eastern Europe. We aren’t just here to participate. We’re here to change the game. By uniting local powerhouses like MaxBet, Adjarabet.com, and Adjarabet.am, we combine deep regional expertise with the scale and strength of Flutter’s global platforms. We’re setting a new standard for entertainment, responsibility, and innovation - powered by real customer signals that shape everything we build. Settling for the status quo isn’t in our DNA. We build systems designed to scale. We’re moving faster, thinking bigger, and putting our customers exactly where they belong: at the heart of every decision. We start by listening to our customers and the communities we serve. What we see, hear, and learn become clear signals, and those signals quickly shape product decisions, better experiences, and responsible innovation. Technology powers our ambition. The Signature System - our operating model - makes our signal-led approach repeatable and scalable across markets. It’s how we move fast and grow with confidence. As part of Flutter, we benefit from the Group’s collective advantage - the Flutter Edge. It allows us to identify success in one market, replicate it across brands, and implement proven ideas quickly - with customers always at the forefront. We’re a team of thousands, driven by a challenger mindset and a shared commitment to lead. We are shaping the future of iGaming in Central and Eastern Europe right here, right now, and our technology and product teams are defining what responsible innovation looks like in practice - not just in theory. We are Flutter Central & Eastern Europe (CEE). Built on experience. Built to lead. Local champions. Global infrastructure. Why choose us At Flutter CEE, people have access to vast opportunities for career growth and self-development. Our employee benefits package goes far beyond offering the minimum: We support our people in becoming their best version at work and beyond - and our benefits reflect that commitment. These are some of the benefits included in our employee package: Generous annual leave Hybrid work Individual health insurance Paid sick leave Paid maternity & paternity leave Family reward Performance & referral bonuses