Freelance Backend Software Engineer

Senior Backend Java Engineer (Freelance Contract) – Hungary

Contract Length: 3+ Months

Start Date: ASAP

Day Rate: 120,000 HUF – 180,000 HUF per day

Location: Hungary

Beyond Sports is looking for an experienced Senior Backend Java Engineer to support the development, scaling, and modernisation of our high-performance backend systems and cloud infrastructure.

This is a hands-on freelance contract opportunity for a senior engineer with deep Java expertise, strong cloud experience, and a passion for building resilient, scalable systems. You’ll work closely with cross-functional engineering teams to refactor core microservices, improve system architecture, and ensure low-latency integrations across our web and mobile platforms.

• Design, refactor, and maintain scalable backend microservices and REST APIs using Java and Spring Boot
• Re-architect existing backend systems to optimize for maintainability, reliability, and throughput
• Implement secure identity, secrets management, and authentication standards across cloud environments
• Integrate third-party systems, including real-time sports data feeds, video streams, and commentary providers
• Deploy and manage containerised services using Docker and Kubernetes
• Provision and maintain cloud infrastructure using Infrastructure as Code (IaC) tools like Terraform
• Build, automate, and manage deployment workflows using modern CI/CD pipelines
• Monitor, troubleshoot, and optimize application and database performance
• Participate in technical planning, architectural discussions, and peer code reviews
• Produce clear, maintainable technical documentation for APIs and core backend systems

• Strong commercial contracting experience with Java and Spring Boot
• Proven background building, deploying, and maintaining applications in production cloud environments (AWS or Azure)
• Hands-on experience with containerisation and orchestration using Docker and Kubernetes
• Expertise in designing and building secure, high-traffic RESTful APIs
• Practical experience writing Infrastructure as Code using Terraform
• Solid working knowledge of relational and NoSQL databases (e.g., PostgreSQL, MySQL, DynamoDB, Cosmos DB)
• Deep understanding of cloud security fundamentals (IAM, secrets management, key vaults)
• Experience setting up and maintaining CI/CD pipelines (e.g., GitLab CI, Bitbucket Pipelines, or ArgoCD)
• Experience with event-driven architectures using Apache Kafka or similar messaging systems
• Prior exposure to performance tuning and cloud cost-optimisation strategies
• Strong automated testing practices (unit, integration, and regression testing)
• Understanding of cloud networking components (VPCs/VNets, API Gateways)