Senior Backend Engineer (Core Team)

About the Role We’re looking for a Senior Backend Developer who thrives in a deeply hands-on environment and enjoys being close to the code on a daily basis. This role is heavily focused on building, optimising, and scaling backend services in a high-load system where performance and reliability are critical. You’ll be working on complex, real-time challenges at the core of our platform - improving latency, ensuring high availability, and making systems more efficient at scale. This is not a coordination-heavy role; it’s for someone who enjoys writing production code, solving tough engineering problems, and seeing the direct impact of their work. If you’re product-driven, take ownership, and prefer a “build first, improve fast” approach while working on systems where every millisecond matters - this role will feel like home. Key Responsibilities Work as part of a cross-functional team owning a core product within the platform Design, build, and deliver new backend features end-to-end in a distributed environment Write high-quality, production-level code daily, contributing directly to a high-load, scalable system Take ownership of services handling financial transactions at scale, with a strong focus on reliability and accuracy Proactively suggest and implement improvements in architecture, processes, and development practices Participate in code and architectural reviews to maintain high engineering standards Solve complex business and technical challenges with pragmatic, efficient solutions Participating in on-call rotations within the squad to ensure the reliability and availability of our systems Play an active role in ongoing tech transformation initiatives across the platform Collaborate closely with engineers, product, and other stakeholders to deliver impactful solutions used by millions globally Requirements Solid experience with Node.js/TypeScript is ideal, but we also welcome experts in other OOP languages such as Java, Python, C++, C#, or Go Strong understanding of asynchronous programming techniques Deep production experience with Kafka: confident reasoning about consumer-group rebalances and their impact on in-flight processing, offset-commit strategies under retries and duplicate delivery, and the limits of "exactly-once" semantics Experience designing idempotent, retry-safe handlers for at-least-once pipelines: transactional outbox, idempotency keys, and deduplication Experience building services with gRPC or similar RPC frameworks Strong knowledge of relational databases such as MySQL or PostgreSQL, plus production experience with at least one NoSQL technology at scale, such as DynamoDB, MongoDB, or Redis Hands-on experience running services on Kubernetes and AWS/GCP: deployment, autoscaling, resource limits, and production debugging Production operations experience: on-call ownership of a high-load system, including incident response, impact assessment, root-cause analysis, and post-incident improvements Nice to Have Experience