Senior Back-End Developer – Full-Time (F/M)

Want to revolutionize the way we learn?
At LumApps, our mission is to create truly groundbreaking learning experiences.
Our motto: More learning moments, better future.

About LumApps Learning
As pioneers in mobile learning, Teach on Mars develops a next-generation digital training platform for companies.

Natively mobile and social, it leverages the latest advances in artificial intelligence to deliver relevant content to users every day and accelerate their skills development.

At the end of , Teach on Mars joined LumApps, a B2B SaaS scale-up that builds innovative, integrated intranets for large European and international companies. By becoming part of LumApps, Teach on Mars extends micro-learning to every employee, seamlessly embedded into the overall employee experience.

About LumApps

• A SaaS platform dedicated to Employee Experience, engaging every employee through personalized communication, on any device, wherever they work, while connecting them with the tools, people, and information they need to be their most productive.
• Our mission: to give employees a sense of belonging and purpose.
• Trusted by + enterprise customers worldwide.
• A team of + Lumies, spread across 11 offices: Lyon, Paris, Sophia-Antipolis, Lille, Barcelona, Hamburg, London, Austin, Tokyo, Zurich and Krakow.

*The role *

Weve recently welcomed a fast-growing software company into our group, which brings with it a rich variety of technologies and approaches. In order to streamline, harmonize, and build the next generation of our SaaS platform, we're looking for someone who doesnt just want to maintain systems, but whos excited by such opportunity. Its a unique chance to leave a lasting mark by shaping a stronger, more scalable foundation for the future.

This is a role for someone who thrives in complex environments, can cut through noise, and wants the satisfaction of leaving something cleaner and stronger than they found it. If youre the type who enjoys real technical challenges and wants to set a product on the right long-term path, keep reading.

*Your main responsibilities*

• Architect for the future: Help us migrate from a patchwork of stacks to a lean, modern, and maintainable back-end.

• Build real impact: Design and implement APIs that serve millions of users, ensuring reliability and scalability.

• Hands-on contribution: Write production-grade code, not just diagrams.

• Raise the bar: Lead by example in code reviews, testing, monitoring, and operational excellence.

• Make tough calls: Influence key technical decisions and own them.

*What were looking for*

Were looking for someone who:

• Brings senior-level expertise in at least two of our core stacks (PHP, C# .NET, Python).
• Has a strong track record of hands-on contributions (e.g., GitHub or equivalent) that demonstrates genuine engagement with building and problem-solving.
• Approaches challenges with both an engineering mindset and a product perspective: pragmatic, resourceful, and comfortable delivering end-to-end.
• Demonstrates solid software fundamentals: clean, maintainable, and scalable code, with a focus on testing and quality.
• Values collaboration and inclusivity, while being able to work autonomously when needed.
• Communicates effectively in professional English, both written and spoken.

Valuable extras:

• Cloud-native chops (AWS, GCP, or Azure).
• Containers & orchestration (Docker, Kubernetes).
• Some front-end awareness (React, Angular).

*Our tech environment*

• Back-end: PHP, C# .NET, Python

• Front-end: React, Angular

• Databases: PostgreSQL, MySQL

• Hosting: GCP & Azure

• Freedom of choice: OS & IDE

*Why Join?*

This isnt just about maintaining what already exists youll play a key role in transforming a fragmented system into a world-class platform.
Its a rare opportunity to make a meaningful impact on technology used by millions of people.

If youre looking for a role where every day is predictable, this may not be the right fit.
But if youre motivated by complex technical challenges, enjoy building cleaner architecture and better systems, and want your work to have a lasting legacy, youll thrive here.

We aim to celebrate diversity and are committed to creating an inclusive environment for all employees. We encourage applications from candidates of all backgrounds, identities, and experiences.