Senior Backend Engineer; Python

Your responsibilities

We are hiring a Senior Backend Engineer (Python) - (F/M/D) to strengthen our web backend. You will join a highly collaborative R&D environment and play a key role in building secure, scalable and reliable backend services that power our platform and external integrations. You will work closely with engineers across teams to provide technical depth for critical backend components while contributing to architectural decisions that support long-term maintainability and growth.

In this role your responsibilities will include:

• Design, build, and maintainPython-based backend services and APIs, with a strong focus on web applications and platform scalability
• Integrate and maintainexternal third‑party APIs and services (e.g. SaaS platforms, partner systems, internal tooling)
• Providetechnical ownership for complex backend components and initiatives and actively contribute toarchitectural discussions, helping shape backend patterns, standards, and long‑term technical decisions
• Support and mentor other engineers throughcode reviews, technical guidance, and knowledge sharing
• Championclean, maintainable, and secure code through testing, documentation, and best practices
• Contribute to the evolution of security‑related backend capabilities, such as authentication and authorization flows, where relevant

• Senior professional experience as a Backend Engineer / Software Engineer
  , using Python web frameworks, ideally FastAPI
• Strong experience building and operating web backends and REST APIs
  , ideally in a microservices architecture
• Comfortable taking ownership, working independently, and contributing to a wide range of technical topics across Backend.
• Solid understanding of
  scalability, performance, and reliability
  considerations in backend systems
• Experience with authentication and authorization concepts (e.g. OAuth 2.0, OpenID Connect) and exposure to IAM, identityfederation, or SSO implementations is a strong advantage, but not required
• Fluent in written and spoken English

We aim to respond to all applications however if you do not hear from us within 30 days from the date of your application, please consider your application unsuccessful. We thank you for your understanding.

Shape the future
Have a direct impact on the electronics industry with our agile and international team.

Feel welcome
Enjoy our startup atmosphere including free lunches in the office canteen and experience our unique coffee culture. Get to know the CELUS team at regular team events and our annual company offsite.

Commute freely
Modern, central location, free metro tickets, free charging for your electric car and free parking.

Learn and develop
Improve your skills with our English/German language classes, trainings and conferences with a yearly budget up to 1000 EUR. Develop your stamina and endurance with an EGYM Wellpass membership.

Decide where and when you work
Enjoy hybrid office environment, flexible working schedule, workation program, additional paid Christmas week holiday.

Relocate easily
Start swiftly and smoothly with our relocation allowance and adaptation program.