Full Stack Engineer

Job Posting Organization:
CERN, the European Organization for Nuclear Research, is at the forefront of scientific research and technological innovation. Established in 1954, CERN has grown to become one of the world's largest and most respected centers for scientific research, employing thousands of scientists, engineers, and support staff from over 100 countries. The organization operates in multiple countries and is dedicated to pushing the boundaries of knowledge in high-energy physics and related fields. CERN's mission is to uncover the fundamental structure of the universe, and it fosters an environment of collaboration and innovation among its diverse workforce.

Job Overview:
As a Full Stack Engineer within the Tools and Services team of the Scientific Information Service Group at CERN, you will play a crucial role in developing and enhancing core open science platforms such as INSPIREHEP and SCOAP

• This position offers an exciting opportunity to work on machine-learning driven discovery and workflow systems that connect publications, data, and software across the high-energy physics community. You will be responsible for developing advanced systems like INSPIRE AI, which utilizes the INSPIRE dataset to provide accurate answers in high-energy physics. Your work will involve backend development using Python, LangChain, and FastAPI, as well as frontend development with React. You will engage in various projects, adapting to changing requirements and collaborating with experts across CERN to deliver impactful services that support thousands of researchers worldwide. This role emphasizes continuous learning and skill enhancement through contributions to open-source projects and tackling unique challenges in the field.

Duties and Responsibilities:

• Develop and maintain INSPIRE AI, focusing on Retrieval-Augmented Generation (RAG) systems that leverage the INSPIRE dataset.
• Design and implement high-quality scientific paper embeddings and optimize backend services using Python, LangChain, and FastAPI.
• Contribute to the development of the React frontend, ensuring a seamless user experience.
• Collaborate with the CERN IT department and external institutions to design and deploy innovative tools and services.
• Engage in agile project management, adapting to shifting requirements and milestones.
• Regularly enhance skills and expertise by participating in open-source projects and addressing unique engineering challenges.
• Ensure the reliability and performance of services used by the global research community.
• Work effectively within a team, contributing to a collaborative and supportive work environment.

Required Qualifications:

• Professional experience in developing and operating production systems over several years.
• Proficiency in Python and LangChain, particularly in designing retrieval-based AI systems.
• Experience in integrating or developing AI-driven features in real-world applications.
• Strong skills in building modern frontend applications using ReactJS.
• Familiarity with relational databases, preferably PostgreSQL, and the ability to write efficient SQL queries.
• Experience in collaborative engineering environments using Git and platforms like GitHub.
• Exposure to multi-component service architectures and MCP servers.
• Strong understanding of software engineering principles and clean coding practices.
• Ability to design and implement features across the full stack, with a creative mindset for improving LLM-driven retrieval systems.

Educational Background:
Candidates must have a professional background in Computer Science or a related field. A Master's degree with 2 to 6 years of post-graduation professional experience is required, or a PhD with no more than 3 years of post-graduation professional experience. Candidates must also be nationals of a CERN Member or Associate Member State and should not have previously held a CERN fellow or graduate contract.

Experience:
The position requires several years of professional experience in software development, particularly in production systems. Candidates should have a strong background in developing AI-driven applications and modern web technologies, with a proven track record of working in collaborative engineering teams.

Languages:
Fluency in spoken and written English is mandatory. Candidates should also be committed to learning French, as it is beneficial for communication within the organization and the local community.

Additional Notes:
The job closing date has been extended until January 9, 2026, at 23:59 CET. The contract duration is 24 months, with the possibility of extension up to a maximum of 36 months. The position requires full-time onsite work, with working hours set at 40 hours per week. The target start date for this position is March 1, 202

• The job reference is RCS-SIS-TS-2025-226-GRAP, and it falls under the field of Software Engineering and IT. The benchmark job classification is 200020 - Computing Engineer. The compensation includes a monthly stipend ranging from 6287 to 6911 Swiss Francs, which is tax-free, along with 30 days of paid leave per year, comprehensive health insurance coverage, family allowances, a relocation package, and opportunities for on-the-job training and formal language classes.