Back-end Java Engineer

Sigma Technology; Lunds kommun; On-site; SEK 900,000 - 1,300,000; Full time

Job summary

Sigma Technology in Lund, Sweden, seeks an experienced Java backend engineer to join a team delivering Find My network services at scale. You will design, produce, and maintain scalable, privacy-focused backends and own end-to-end responsibilities from design to production in a fast-changing roadmap.

The role emphasizes autonomy, problem-solving, and collaboration across multiple teams, with focus on concurrency, reliability under load, and clear technical documentation for both technical and

Qualifications

• 5+ years of production experience with Java, including memory model, GC tuning and advanced concurrency utilities
• Proven experience building scalable customer-facing web services addressing auth, availability, reliability and performance under load
• Strong understanding of distributed systems concepts like consistency, partitioning, and failure modes
• Experience with data storage and caching technologies such as Cassandra, Redis, or Memcached
• Experience writing REST-based services using frameworks like Netty
• Knowledge of CI/CD tools and full automation testing
• Excellent written and verbal communication for design docs and cross-team collaboration

Responsibilities

• Design, develop, and maintain scalable backend services for Find My network
• Manage services end-to-end from design to production deployment
• Collaborate with multiple teams to manage cross-team dependencies
• Adapt plans based on evolving goals, threat models, and partner requirements
• Build internal frameworks for use across teams and communities
• Investigate and debug complex concurrency and production issues under load
• Write clear technical documentation and communicate decisions to stakeholders

Skills

Java

Concurrency

Distributed systems

REST/Netty

Caching technologies

CI/CD

Docker

Kubernetes

Maven

Security & auth

Tools

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

Basic Qualifications

• 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, 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

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