Principal Java Engineer - Backend Platform

Principal Java Engineer - Backend Platform Hawk-Eye Innovations - Budapest Salary: HUF 1.8M - 2.6M per month Contract: Full-Time, Permanent Location: Hybrid - minimum 2 days per week in office, Budapest ABOUT THE ROLE The Principal Software Engineer (Full-Stack, Backend-leaning) is a senior engineer responsible for the backend architecture, data pipelines, and API layer of a new sports technology product, while remaining capable of contributing to frontend development as needed. This role sits within a small, fast-moving product engineering team and requires someone comfortable owning end-to-end technical delivery across the stack, with backend and data work as the primary focus. WHAT YOU’LL BUILD You will be a core contributor to a new backend platform being built from scratch. The work spans the full data journey - from ingestion at the edge through to storage, transformation, and delivery to end users. Key areas of focus include: - Low-latency data pipelines that ingest and process live sports tracking data, with strict latency requirements for time-critical outputs delivered to coaches and analysts in near real-time. - Event-driven processing using Kafka for streaming data and control messages between on-site devices and cloud services, handling both fast-path live outputs and asynchronous post-processing workflows via SQS and AWS Batch. - Cloud infrastructure on AWS, including Greengrass for edge-to-cloud orchestration, S3 for video and data storage, and Lambda for lightweight processing tasks. - Data transformation and aggregation layers that normalise tracking outputs, store them in a data lake, and make them available to downstream consumers via clean API contracts. - REST and WebSocket APIs that serve both a live data product for immediate consumption and an insights portal for historical analysis and performance comparison. - Observability and reliability - instrumentation, logging, and tracing are built in from the start, not bolted on. The platform needs to run 24/7 without on-site support. KEY RESPONSIBILITIES - Design and build backend services and APIs (REST/WebSocket) supporting data ingestion, transformation, and delivery to frontend and downstream consumers, with particular attention to latency and throughput given real-time processing requirements. - Own data storage and pipeline architecture, including integration with streaming/event infrastructure. - Implement authentication and authorisation in line with the team's chosen cloud identity and access management approach. - Provide technical direction and review for frontend development (React/TypeScript), working closely with frontend engineers to align on approach, component contracts, and data shapes - this is a collaboration and oversight function rather than day-to-day frontend delivery. - Collaborate closely with computer vision/data science engineers to define and consume data contracts. - Participate in technical decision-making for a product in active development, including architecture choices with long-term implications for scale, latency, and maintainability. - Contribute to technical leadership of the wider engineering team, given the seniority of this role. SKILLS AND EXPERIENCE - Strong backend engineering background with production experience in Java (required). - Demonstrated experience building low-latency, high-throughput systems - this is a core requirement, not a nice-to-have. - Working knowledge of a modern frontend framework such as React/TypeScript, sufficient to review and direct frontend work rather than deliver it independently. - Experience with cloud infrastructure and event-driven architectures (e.g. Kafka or equivalent streaming technology). - Experience designing and evolving API contracts (OpenAPI or similar) in a fast-moving, still-evolving product environment. - Familiarity with modern cloud identity and access management approaches (e.g. AWS Cognito or equivalent) is a plus. - Strong communication skills - able to work di…