Senior Java Developer Drive architecture and backend development in a complex migration program with Java, Spring Boot, Kubernetes, and high-impact API design. Skicka ansökan About the Company At Avaron, you get the security of permanent employment combined with the variety of working at different customers. We place specialists across everything from tech, IT and industry to project management and business support – and whatever the assignment, you have a consultant manager who is there for you and your development. About the Role You will help shape backend services at the heart of a large customer migration program. The assignment centers on a demanding flow where customer identification, stack determination, migration tracking, and application routing need to work together with high accuracy and low latency. You will work in an environment where APIs, data flows, and migration logic must stay reliable while customers move between old and new application stacks. This role combines hands-on Java development with clear architectural influence, making it a strong opportunity if you enjoy solving complex backend challenges and guiding technical direction. Job Description You will design and build Java and Spring Boot REST APIs for customer identification, stack lookup, migration tracking, and routing. You will create flexible identification mechanisms that can support additional identifiers as business and migration needs evolve. You will develop batch processing for loading, updating, and maintaining customer migration and stack information. You will enable frontend applications and UI flows with backend services for lookup, status visibility, and redirection. You will design services that handle transitional migration states safely, including routing while migration is in progress. You will ensure solutions are secure, scalable, observable, resilient, and built with strong validation, caching, logging, monitoring, and error handling. You will create automated unit, integration, and API tests and contribute to CI/CD pipelines and containerized deployments. You will guide architectural decisions, evaluate trade-offs, and align services, integrations, and data flows with long-term technical goals. You will collaborate closely with frontend developers, architects, DevOps engineers, product owners, and migration teams. Requirements Strong experience with Java 10+ Strong experience with Spring Boot and Spring Framework Solid experience in REST API and microservice design Experience with Spring Data JPA / Hibernate Experience with SQL and relational databases Experience with batch processing, preferably Spring Batch Experience designing lookup and routing services Experience with API security using OAuth 2.0 / OpenID Connect / JWT Experience with unit and integration testing using JUnit, Mockito, Testcontainers, or equivalent Experience with Maven or Gradle, Git, CI/CD, Docker, and Kubernetes Strong architectural knowledge and the ability to define target architecture, evaluate trade-offs, establish design principles, and guide the team in complex architectural matters Experience with logging, monitoring, metrics, and distributed tracing Fluent in Swedish and English Nice to have Experience with large-scale customer or platform migrations Experience designing systems that support old and new application stacks simultaneously Experience with customer identity or identifier mapping and resolution Experience with migration-state management and rollback scenarios Experience with event-driven architecture and messaging technologies such as Kafka Experience with Redis or similar caching technologies Experience with Azure or AWS cloud platforms Experience with API gateways and traffic-routing solutions Experience with high-volume batch data processing and reconciliation What We Offer Permanent employment at Avaron AB Occupational pension Wellness allowance of SEK 5,000 per year Application Selections are made on an ongoing basis – apply as soon as you can. Platser Stockholm Distansarbete Hybridarbete Stockholm Om Avaron AB Avaron förser företag i hela Sverige med tekniska konsulter och specialister. Vi fokuserar på IT, mjukvaruutveckling, teknik, projektledning och andra tekniska domäner. Grundat 2018 av en mjukvaruingenjör som tröttnade på bemanningsföretag som inte förstod rollerna de rekryterade till. Rekryteringsverktyg från Teamtailor