Backend Developer (Java / Spring Boot)

About Cronos Europa Portugal Cronos Europa Portugal is the Lisbon delivery centre of Cronos Europa, part of the Cronos Group — a technology federation of 9,000+ professionals and 600+ competence centres across Europe. From our office at IDB Lisbon we deliver application development, architecture, and IT operations for major European organisations, working as an integrated nearshore extension of our clients' teams. This position is with Cronos Europa Portugal: the person contracts directly with us, as an employee or as a B2B contractor, joins our Lisbon team and is assigned to a long-term client engagement. About the client A major European organisation operating mission-critical aviation systems The client's engineering teams work closely with its functional experts to make European aviation safer and more efficient. They build a wide variety of data-driven solutions that combine operational expertise, technical expertise and uniquely valuable European aviation data. The solutions run mainly on Microsoft Azure and are deployed through Azure DevOps pipelines. Teams follow SAFe / Agile. AI-assisted development is part of how the teams work, and the client values demonstrated experience over familiarity with the concepts. The role includes regular work on site at the client in Brussels: about 30 working days per year, typically 5 consecutive working days every 2 months. There is some flexibility in how these days are spread. Candidates must accept this from the start. About the Role We are looking for senior Backend Developers to join one of the client's development teams and build and run the services behind its solutions. The current stack is Java and Spring Boot, running on Microsoft Azure and deployed through Azure DevOps. The shape of the profile A senior Java / Spring Boot engineer who designs, builds and runs services in production - and closely matches every technical requirement below. The client prefers full stack developers. Backend candidates are considered when they are strong and match the technical requirements closely: Java and Spring Boot, Azure and Azure DevOps, PostgreSQL and Oracle, and several architectural styles. Key Responsibilities BUILD Design and build backend services and APIs Integrate with other systems through well-defined contracts Design and evolve the data model for each solution ENGINEERING PRACTICE Apply clean code, automated testing, continuous integration and deployment Take part in design and code reviews RUN Run your services in production: monitoring, alerting, incident response WORKING IN THE TEAM Refine requirements with the Product Owner and functional experts, and assess technical feasibility Review requirements, challenge assumptions when needed, and raise concerns about feasibility or clarity Requirements MANDATORY 5+ years building production backend services with Java and Spring Boot Strong software design and enterprise integration patterns, with the judgement to pick the right one or keep it simple Experience with several architectural styles - for example hexagonal, modular monolith, microservices, event-driven Hands-on Microsoft Azure and Azure DevOps Data modelling and database design - PostgreSQL and Oracle Solid delivery practice: automated testing, quality gates, DevSecOps Experience in SAFe / Agile teams Experience with AI-assisted development, including handling the problems it introduces Fluent English, written and spoken - see the language requirement below SENIORITY Senior - minimum 5 years building production backend services with Java and Spring Boot. LANGUAGE - HARD REQUIREMENT Fluent English, written and spoken, is mandatory - C1 is the level we are aiming for. All project work, documentation and meetings happen in English with an international team. French is a plus. PREFERRED / ADDED VALUE Event-driven systems - Kafka, Azure Service Bus Cosmos DB Performance testing Some front-end experience (React / TypeScript) - brings the candidate closer to the preferred full stack profile French Informations Contract Direct with Cronos Europa Portugal: employment or B2B contractor, no intermediaries Engagement Full-time Location IDB Lisbon - Praca Jose Queiros, 1, Bloco C, 4.o andar Office presence Minimum 3 days per week on site Travel About 30 working days per year on site in Brussels (typically 5 consecutive days every 2 months) Start Expected from January 2027 (to be confirmed) Why Cronos Group? We’ll propose you: An attractive salary package A good work-life balance environment The assurance of working in cutting-edge technologies in an entrepreneurial spirit. The opportunity to develop your skills thanks to tailor-made training courses according to your needs A good job in a friendly place If you wish to integrate a dynamic structure on a human scale while working with the latest technologies, don't wait anymore and join Cronos!