Back- end Java Engineer

Sigma Group; Lunds kommun; On-site; SEK 1,100,000 - 1,450,000; Full time

Job summary

Sigma Group in Lund, Sweden, seeks a senior backend engineer to design, develop, and maintain scalable Find My backend services. You’ll own components end-to-end, from design to production, in a fast-changing roadmap environment.

The role emphasizes autonomy, problem-solving, and collaboration across teams, with focus on privacy, reliability, and performance under heavy load.

Qualifications

• 5+ years of production experience with Java.
• Experience building REST-based services.
• Knowledge of CI/CD tools and automated testing.
• Excellent written and verbal communication.

Responsibilities

• Design, develop, and maintain highly scalable, reliable backend services supporting the Find My network.
• Manage services end-to-end including design, production deployment, and ongoing maintenance.
• Work collaboratively with multiple teams managing cross-team dependencies without compromising quality.
• Adapt rapidly to shifting priorities and rewrite plans based on evolving goals, threat models, and partner requirements.
• Build frameworks used internally and by other teams and developer communities.
• Investigate and debug complex concurrency and production issues that appear only under real load or concurrency conditions.
• Write clear technical documentation and communicate decisions effectively to both technical and non-technical stakeholders.
• Strong understanding of distributed systems concepts such as consistency, partitioning, and failure modes.

Skills

Java expertise

Concurrency

Problem solving

Communication skills

Tools

Cassandra

Redis

Memcached

Netty

Maven

Docker

Spinnaker

Kubernetes

Job description

Join us at Sigma to be part of a team of consultants that will work at Apple with features relating to the Find My network. You will be part of the back-end services that locate lost devices even without network connections, using a crowd-sourced network of nearly a billion devices worldwide. You will work on designing, producing, and maintaining scalable, reliable, and privacy-focused services that operate at massive scale. This is a highly autonomous role where you'll handle everything from design to production within a fast-changing roadmap environment. Strong problem-solving skills and the ability to adapt to shifting priorities are crucial.

• Design, develop, and maintain highly scalable, reliable backend services supporting the Find My network
• Manage services end-to-end including design, production deployment, and ongoing maintenance
• Work collaboratively with multiple teams managing cross-team dependencies without compromising quality
• Adapt rapidly to shifting priorities and rewrite plans based on evolving goals, threat models, and partner requirements
• Build frameworks used internally and by other teams and developer communities
• Investigate and debug complex concurrency and production issues that appear only under real load or concurrency conditions
• Write clear technical documentation and communicate decisions effectively to both technical and non-technical stakeholders
• 5+ years of production experience with deep expertise in Java, including memory model, garbage collection tuning, and concurrency utilities beyond synchronized
• Proven experience building and scaling customer-facing web services addressing authentication, authorization, availability, spam control, reliability, and performance tuning under load
• Strong understanding of distributed systems concepts such as consistency, partitioning, and failure modes
• Experience with data storage and caching technologies like Cassandra, Redis, or memcached
• Experience writing REST-based services using frameworks like Netty
• Knowledge and experience with CI/CD tools and full automation testing
• Strong written and verbal communication skills for explaining technical decisions, writing design documents, and collaborating across disciplines

Preferred additional skills, personal traits and experience

• Knowledge of cryptography standards and protocols, including 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