Middle/Senior Java Developer

Employment: Full-time Experience level: Mid-Senior Level Job Description Design, develop, and maintain scalable Java backend services and internal frameworks Participate in architecture discussions and contribute to technical solution design Build and support customer-facing services with a focus on reliability, availability, security, and performance Investigate and resolve complex production issues related to concurrency and distributed systems Work with authentication, authorization, caching, data storage, and service integrations Collaborate with multiple engineering teams and coordinate technical dependencies Participate in code reviews, automated testing, CI/CD processes, and release activities Prepare technical documentation and communicate technical decisions to stakeholders Take end-to-end ownership of features and technical solutions from concept to production Qualifications 4+ years of commercial experience in Java backend development Strong hands-on experience with Java and distributed systems Deep understanding of Java internals, including the Java Memory Model, garbage collection, concurrency, and multithreading Experience debugging production issues in high-load environments Strong knowledge of distributed systems concepts, including consistency, reliability, partitioning, and failure handling Experience building and scaling customer-facing backend services Experience with authentication and authorization mechanisms Hands-on experience with Cassandra, Redis, Memcached, or similar technologies Experience developing REST-based services using Netty or similar frameworks Experience with CI/CD pipelines and automated testing Strong analytical and problem-solving skills Upper-Intermediate or higher level of English WILL BE A PLUS Knowledge of cryptography standards and protocols such as PKCS, KMIP, X.509, AES, KDF, and CA Experience working with security- and privacy-sensitive systems Familiarity with machine learning systems or algorithms Experience with GitHub Experience with Maven, Docker, Kubernetes, Spinnaker, or similar tools Additional Information PERSONAL PROFILE Strong sense of ownership and accountability Ability to work independently in autonomous engineering teams Analytical and problem-solving mindset Attention to detail and engineering quality Strong communication and collaboration skills Ability to work effectively in complex distributed environments Company Description Are you passionate about building scalable backend systems that operate under real production load? We are looking for a Middle/Senior Java Backend Developer to join a long-term onsite project in Malmö, Sweden, focused on privacy-sensitive distributed services used at global scale. You will join a small, autonomous engineering team where ownership, technical excellence, and collaboration are highly valued. The role involves full-cycle development, from architecture discussions and implementation to deployment and production support. We at Sigma Software offer the opportunity to work on technically challenging products in an engineering-driven environment with modern technologies, high-quality standards, and long-term project stability. CUSTOMER Our Customer is a global technology company operating in the consumer electronics and digital services domain. The company develops large-scale platforms and infrastructure used by millions of users worldwide, with a strong focus on privacy, reliability, and seamless user experience. PROJECT The project focuses on developing and supporting large-scale backend services operating in a privacy-sensitive environment under high production load. The team designs and maintains distributed systems with strict requirements for reliability, scalability, security, and performance. Engineers work in cross-functional teams and contribute to the entire software development lifecycle.