Back- end Java Engineer

Sigma Group; Lunds kommun; On-site; SEK 900,000 - 1,100,000; Full time

Job summary

Sigma Group is seeking an experienced backend engineer to join a team building and maintaining scalable Find My network services for Apple. You will own design, production deployment, and ongoing maintenance in a highly autonomous role with a shifting roadmap.

The role demands deep Java expertise, knowledge of distributed systems, and experience with REST-based services, concurrency, and data stores like Cassandra/Redis. Strong communication across teams is essential.

Qualifications

• 5+ years of production experience with Java and backend services.
• Experience building scalable, privacy-focused services under heavy load.
• Familiarity with REST-based services and Netty.

Responsibilities

• Design, develop, and maintain highly scalable backend services for Find My network.
• Manage end-to-end service lifecycle from design to production deployment.
• Collaborate across teams to manage cross-team dependencies without sacrificing quality.
• Adapt plans quickly in response to evolving goals and threat models.
• Build internal frameworks used by multiple teams and communities.
• Investigate concurrency and production issues under real load.
• Write clear technical documentation and communicate decisions.

Skills

Java

Memory management

Concurrency utilities

Distributed systems

REST services

Netty

CI/CD

Automation testing

GitHub

Docker

Kubernetes

Maven

Redis

Cassandra

Memcached

Tools

GitHub

Maven

Docker

Spinnaker

Kubernetes

Netty

Redis

Cassandra

Memcached

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