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

About the Role

Beyond Sports is looking for an experiencedSenior 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.

Key Responsibilities

• 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

Required Skills & Experience

Essential

• Strong commercial contracting experience withJava andSpring Boot

• Proven background building, deploying, and maintaining applications in production cloud environments (AWS orAzure)

• Hands-on experience with containerisation and orchestration usingDocker andKubernetes

• Expertise in designing and building secure, high-trafficRESTful APIs

• Practical experience writing Infrastructure as Code usingTerraform

• 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, orArgoCD)

Desirable

• Experience with event-driven architectures usingApache 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)