Junior Software Engineer (TE-MPE-CB-2026-16-GRAE)

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CERN is seeking a Junior Software Engineer to help redesign and deploy the LHC Post-Mortem system, building a scalable architecture with streaming data, long term storage and containerised services, in close collaboration with engineers, physicists and operations teams in Geneva onsite. You will develop robust Java Spring Boot services and Java and C++ clients, apply DevOps practices in Kubernetes, create comprehensive test suites and lead a data migration from Oracle to new storage. To stand out, show hands on Java backend experience, Spring Boot, Kubernetes, CI/CD and IaC, plus knowledge of concurrency, databases and networking; demonstrate the ability to refactor large codebases and work with stakeholders, and prove English fluency with a commitment to learn French. Ensure eligibility: maximum two years post graduation, Bachelor's or Master's, no prior CERN fellowship, apply by 26 February 2026 23:59 CET.

Job Description

Are you interested in building reliable, large-scale control and data systems for one of the world's most complex scientific machines? In this role, you will contribute to the redesign and deployment of the LHC Post-Mortem system, a critical infrastructure used to analyse and understand machine events such as beam losses, magnet quenches, and beam dumps.

You will work on the evolution of the system towards a modern, scalable architecture based on streaming technologies, long-term data storage, and containerised services, ensuring high performance, reliability, and readiness for future LHC operation. As part of CERN's Machine Protection and Electrical Integrity Group, you will collaborate closely with engineers, physicists, and operations teams to support safe and efficient accelerator operation during Run 4 and beyond.

Your responsibilities

• Develop and maintain robust Java services (using Spring Boot) and client libraries (Java and C++) based on the existing PM system code, ensuring high reliability and maintainability.
• Leverage DevOps practices to automate deployment, monitoring, and scaling of the new system in a Kubernetes environment.
• Create comprehensive test suites to validate the system's functionality and performance under real-world scenarios and throughput requirements.
• Implement a data migration solution to transition from the legacy Oracle-based storage to the new long-term storage.
• Collaborate closely with stakeholders and system clients to understand and meet their requirements, ensuring seamless integration with existing workflows.

More information here.

Your profile

• Experience with Java back-end development, Kubernetes and DevOps practices.
• Working knowledge of Scrum/Kanban methodologies.
• Strong aptitude for understanding large code bases and refactoring for improved maintainability.

Skills

• Java (Spring Boot), C++.
• Understanding of concurrency and multithreading.
• Networking knowledge.
• Familiarity with relational databases.
• Basic Kubernetes and Apache Kafka knowledge.
• Familiarity with DevOps (CI/CD, IaC, monitoring).
• Ability to work effectively in a team and participate in design discussions.
• Spoken and written English, with a commitment to learn French.

Eligibility criteria:

• You are a national of a CERN Member or Associate Member State.
• By the application deadline, you have a maximum of two years of professional experience since graduation in Computer Science or Software Engineering (or a related field) and your highest educational qualification is either a Bachelor's or Master's degree.
• You have never had a CERN fellow or graduate contract before.
• Applicants without University degree are not eligible.
• Applicants with a PhD are not eligible.

Additional Information

Job closing date: 26.02.2026 at 23:59 CET.

Contract duration: 24 months, with a possible extension up to 36 months maximum.

Working hours: 40 hours per week

Job flexibility: Fully Onsite

Target start date: 01-April-2026

Job reference: TE-MPE-CB-2026-16-GRAE

Field of work: Software Engineering and IT

Benchmark job: 200020 - Computing Engineer

Global Benefits

• A monthly stipend between 5266-5793 Swiss Francs per month (tax free) depending on your degree.
• 30 days of paid leave per year plus 2 weeks annual closure.
• Coverage by CERN’s comprehensive health insurance scheme (for yourself, your spouse and children), and membership of the CERN Pension Fund.
• Family, child and infant monthly allowances depending on your individual circumstances.
• A relocation package (installation grant and travel expenses) depending on your individual circumstances.
• Possibility to extend your contract up to 36 months.
• On-the-job and formal training including language classes.

Overview of CERN - Discover a world where the impossible is made possible!

At CERN, the European Organization for Nuclear Research, we are pushing the frontiers of science and technology. Our groundbreaking work brings together not only physicists but also a diverse range of professionals from engineering, technical, scientific, and administrative fields. Together, we foster an environment where innovation and collaboration thrive.

Every day, we face exciting new challenges and opportunities to contribute to cutting-edge research that shapes our understanding of the universe. We meet these challenges through the diverse perspectives within our teams, ensuring every contribution is valued and driving our shared sense of inclusion and purpose. Diversity is a core value of CERN since its foundation, and it remains central to our mission and continued success.

If you are ready to be part of a dynamic, inclusive community pushing the boundaries of knowledge, CERN is the place where your curiosity and skills can thrive. Be part of our mission to uncover what lies at the heart of the universe! TAKE PART!

More information about us, here: careers.cern