Senior Java Backend Engineer

Sigma Group; Lunds kommun; On-site; SEK 900,000 - 1,200,000; Full time

Job summary

Sigma Group in Malmö, Sweden is seeking an experienced Senior Java Backend Engineer to join our dynamic team. You will develop and maintain scalable, high-performance Java backend services, and collaborate with cross-functional teams to design and implement new features.

The role requires a deep understanding of distributed systems, production experience, and familiarity with data storage and caching technologies such as Cassandra and Redis.

Qualifications

• 5+ years of production experience in backend Java development.
• Deep understanding of Java memory model, garbage collection, and concurrency utilities.
• Experience debugging production issues under real load and concurrency.
• Proven expertise in building and scaling customer-facing web services including authentication and authorization.

Responsibilities

• Develop and maintain scalable, reliable, and high-performance Java backend services.
• Collaborate with cross-functional teams to design and implement new features.
• Investigate and resolve complex production issues under real-world concurrency and load.
• Optimize application performance including tuning garbage collection and allocation pressure.
• Read and analyze source code of dependencies to solve problems beyond available documentation.
• Write clear design documents and communicate technical decisions to stakeholders.
• Participate in CI/CD practices and ensure high-quality automated tests are in place.

Skills

Java backend

Distributed systems

Production experience

Concurrency

RESTful services

CI/CD

English communication

Netty

Maven

Docker

Tools

Cassandra

Redis

memcached

Netty

Maven

Docker

Kubernetes

Spinnaker

Job description

We are seeking an experienced Senior Java Backend Engineer to join our dynamic team in Malmö, Sweden. This role demands deep expertise in Java and a strong background in building and scaling customer-facing web services. The ideal candidate will have significant production experience, a robust understanding of distributed systems, and familiarity with various data storage and caching technologies. You will be responsible for developing reliable, high-performance services, troubleshooting complex production issues, and contributing to architecture and design decisions in a collaborative environment.

• Develop and maintain scalable, reliable, and high-performance Java backend services
• Collaborate with cross-functional teams to design and implement new features
• Investigate and resolve complex production issues under real-world concurrency and load
• Optimize application performance including tuning garbage collection and allocation pressure
• Read and analyze source code of dependencies to solve problems beyond available documentation
• Implement and enhance authentication, authorization, and spam control mechanisms
• Contribute to the design of distributed systems ensuring robustness and fault tolerance
• Write clear design documents and communicate technical decisions effectively to both technical and non-technical stakeholders
• Participate in CI/CD practices and ensure high-quality automated tests are in place
• 5+ years of production experience in backend Java development
• Deep understanding of Java memory model, garbage collection, and concurrency utilities
• Experience debugging production issues under real load and concurrency
• Proven expertise in building and scaling customer-facing web services including authentication and authorization
• Strong knowledge of distributed systems concepts such as consistency, partitioning, and failure modes
• Hands-on experience with data storage and caching systems like Cassandra, Redis, or memcached
• Experience writing RESTful services using Netty or similar frameworks
• Proficiency with CI/CD tooling and full automation testing
• Excellent written and verbal communication skills in English

Preferred additional skills, personal traits and experience

• Knowledge of cryptography standards and protocols (PKCS, KMIP, X.509, AES, KDF, CA)
• Familiarity with machine learning systems, frameworks, and algorithms
• Experience with GitHub and build and deployment tools such as Maven, Docker, Spinnaker, and Kubernetes

Software development embedded systems, System design, System development, Software, Software development, Digitalisation

2026-08-26

2026-09-30

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