Full Stack Developer (Java / Spring Boot + React)

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.

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.

We are looking for senior Full Stack Developers to join one of the client's development teams and deliver features end to end, from the user interface to the backend services and the data.

The current stack is Java and Spring Boot with React and TypeScript, running on Microsoft Azure and deployed through Azure DevOps.

A senior engineer who delivers a feature from the database to the screen: Java / Spring Boot on the back end and React / TypeScript on the front end.

Both tiers at a professional level. A CV that is all front end with Java only as a side note, or all back end with no real React work, does not fit this profile.

The client also values good interface design: clear, consistent and easy-to-use screens, even for applications with complex data.

BUILD

• →Design and build backend services and the web front-ends that use them
• →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 features 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

MANDATORY

• 5+ years building production applications with Java / Spring Boot and React / TypeScript
• Strong software design and enterprise integration patterns, with the judgement to pick the right one or keep it simple
• Experience with several architectural styles on both tiers
• 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 applications with Java / Spring Boot and React / TypeScript.

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

• Angular
• Event-driven systems
• Performance testing
• Aviation or air traffic management background
• French

• 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)