Python Software Engineer

What you'll do

As a Python Software Engineer with a strong interest in both API development and desktop application engineering (with PyQt6), you will work on tools at the heart of CERN’s accelerator complex, used daily across operations, engineering, and physics.

This role spans the Python APIs that interface to the CERN control system, and the PyQt6-based desktop applications built on top of them.

On the API side, you will develop frameworks, libraries, and bindings integrating tightly with backend control system services, with a strong emphasis on developer experience, robustness, and long-term maintenance.

On the UI side, you will work on applications for operating, monitoring, and configuring accelerator systems, ensuring reliable, responsive, and effective user experiences.

You will collaborate with colleagues across the organisation, contributing to design reviews, documentation, training, and technical support, while staying abreast of relevant emerging technologies and playing an active part in shaping the future of CERN’s accelerator control system.

Your responsibilities

Design and maintain Python bindings to the accelerator control system, using a range of technologies such as REST, gRPC, event-driven messaging (e.g. ZMQ), as well as bindings to existing C++ and Java libraries.
Build reusable components, widgets, and libraries supporting control application development at CERN.
Develop and maintain a number of PyQt-based control applications used in the CERN Control Centre.
Contribute to the selection and configuration of a coherent DevOps toolchain for Python, covering dependency management, packaging, testing, CI/CD, and deployment monitoring.
Collaborate with user communities to establish and document best practices for developing Python-based control applications.
Contribute relevant developments back to the open source community.
Take ownership of one or more key systems or tools, driving their evolution through active engagement with stakeholders and structured follow-through.
Mentor junior engineers, sharing knowledge and supporting their growth as they contribute to the above areas.

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Your profile

Extensive experience with Python, including typed Python and asynchronous programming patterns.
Advanced knowledge of API and application design, with proven experience designing and evolving client-oriented APIs and SDKs.
Solid grasp of platform engineering principles and modern software engineering practices, including quality assurance and DevOps.
Knowledge of Qt and its Python bindings (PyQt or PySide) is a plus; willingness to learn is equally valued.
Experience in UI design with a strong focus on usability and developer experience is desirable.
Comfortable working across a broad and evolving technology landscape, with the curiosity and initiative to develop new expertise as the role demands.
Master's Degree or equivalent relevant experience in the field of Computer Science or a related field.

Your skills

Knowledge of programming techniques and languages.
Design of databases/repositories.
Architecture and design of ICT systems.
Identification and selection of relevant emerging ICT technologies.
Conceptualising, designing and developing user experiences and interfaces.
Delivers high quality work on time and fulfils expectations.
Adopts a pragmatic approach; understands the value of adopting generic rather than gold -plated' technical solutions.
Contributes to promoting a positive atmosphere in the team through an optimistic and constructive attitude; addresses issues.
Works conscientiously and reliably; delivers on promises.
Adapts quickly and resourcefully to shifting priorities and requirements.
Spoken and written English, with a commitment to learn French.

Ideal start date: 01/09/2026

Contract duration (in months): 60

Grade range: 6

Benchmark job: 200020 - Computing Engineer

Job flexibility: Hybrid

Global Benefits at CERN

A minimum net entry-salary of 9236 Swiss Francs per month, increasing in line with your years of relevant experience.
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, removal, travel expenses) depending on your individual circumstances.
Possibility to extend your contract up to 8 years + eligibility for indefinite contract tenure.

Let's get you ready

Be sure to meet the eligibility criteria

You are a national of a CERN Member State or Associate Member State. Currently, we cannot consider applications from Pakistani and Lithuanian nationals for positions with a 2026 start date, as the ceiling defined under Article II.5 of the Associate Membership Agreement has been reached.
You have relevant qualifications and professional experience.
If you have previously held a Staff contract at CERN, you will not be eligible for these positions.
Please pay attention to the additional criteria and requirements for this specific position and mentioned above.

You will need these documents to complete your application

Your CV (English or French)
Any document you consider relevant to your application

Your CERNDepartment

The BE department is at the heart of CERN's accelerator complex.

Its mission is to lead the development, construction, and operation of advanced particle accelerators, and to provide cutting-edge technology solutions that enable new discoveries in fundamental physics. Committed to promoting a culture of excellence, creativity and collaboration, individuals from diverse backgrounds contribute to the advancement of science and technology, as well as engaging in scientific education, outreach, and broader knowledge and technology transfer initiatives.

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!

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Still have a doubt ? Here are the most frequently asked questions

What should I expect during my first week at CERN?

Your onboarding at CERN includes a comprehensive induction programme, which starts with an official welcome session at the beginning of each month. In addition, you will receive important information both before and after your arrival to ensure a smooth transition into your new role. This process is designed to help you get acquainted with CERN’s environment, your team, and the tools and systems you’ll be using.
How big would the team be?

The size of the team you'll be working with at CERN depends on the specific role and department. Some teams are small and highly specialized, while others are larger and more interdisciplinary. During the interview process, you'll have the opportunity to learn more about the team structure for the position you are applying for.
What is the working language at CERN?

The working languages at CERN are English and French. However, it is not always mandatory to speak both languages to work at CERN. We offer language training to help you acquiring the other language.
What support does CERN provide for relocation?

CERN does not offer direct assistance with relocation. However, depending on your role and specific criteria, you may be eligible for certain benefits such as an installation allowance and coverage of travel expenses to join CERN. These benefits are designed to help ease the transition when relocating to the Geneva area. For more information, please consult the “Salary, Benefits and Support“ page.
Do I need a visa to work at CERN?

Whether you need a visa to work at CERN depends on your nationality and the duration of your stay. CERN assists with the necessary visa and work permit processes for its employees and visitors. The specific requirements will be communicated to you during the recruitment process.
What would my salary be?

Salaries at CERN are determined by a structured scale. Salaries are based on your role, qualifications, and experience, and are not subject to negotiation. Specific details will be provided as your application progresses. For more information, please refer to the dedicated page.