Senior Back-End Developer (PHP, C# .NET, Python) – 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 2023, 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 700+ enterprise customers worldwide.
- A team of 600+ Lumies, spread across 11 offices: Lyon, Paris, Sophia-Antipolis, Lille, Barcelona, Hamburg, London, Austin, Tokyo, Zurich and Krakow.
*The role *
We’ve recently acquired a software company that’s grown fast but left us with a jungle of tech stacks and languages. We’re not looking for someone to just “maintain” it, we need a builder who sees this as a chance to bring order, simplify, and shape the future of our SaaS platform.
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 you’re 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 we’re looking for*
We’re not interested in average. We want someone who:
Has senior-level expertise in at least 2 of our core stacks (PHP, C# .NET, Python).
Comes with a serious GitHub or equivalent track record that shows passion for building.
Thinks like an engineer and a product owner: pragmatic, entrepreneurial, and able to deliver end-to-end.
Brings rock-solid fundamentals: clean code, maintainability, scalability, testing.
Thrives on autonomy but works inclusively with others.
Speaks and writes English fluently.
Nice-to-have superpowers:
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 is not a cushy maintenance gig. You’ll be the person who takes a fragmented system and turns it into something world-class. It’s a chance to make a lasting impact on a platform used by millions.
If you want a comfortable job with no headaches, this isn’t for you.
If you want to roll up your sleeves, take on a gnarly technical challenge, and leave a legacy of cleaner architecture and better systems, you’ll love it here.
- Department
- Teach on Mars
- Locations
- Sophia-Antipolis, Tassin-la-Demi-Lune, Lyon, Paris, Kraków
- Remote status
- Hybrid

LumApps is...
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A company that has been growing for more than 10 years
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Nearly 400 Lumies worldwide
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More than 700 customers
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Offices in Austin, Paris, Lyon, Lille, Sophia-Antipolis, London, Tokyo, Hamburg and Barcelona
Our greatest pride?
Our talents come from a variety of backgrounds and are passionate about creating a unique, powerful solution that delivers the best possible employee experience.
About LumApps
LumApps is an Employee Experience Platform that helps organizations thrive in a digital environment by connecting and empowering employees with purpose and belonging.
Already working at LumApps?
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