We're not looking for someone to simply write code.
We're looking for a Senior Java Developer who wants to influence architecture, mentor other engineers, and take ownership of systems that power communication for users around the world.
At Onoff, we're scaling fast. We've launched new products, continue to grow across Europe, and are building the next generation of telecom SaaS. Now we're looking for an experienced engineer who wants to leave a lasting mark on both our product and our engineering culture.
This isn't a feature factory. It's a place where experienced engineers have a real voice.
💡 Drive Technical Direction – Influence architecture, challenge ideas, and help shape engineering decisions.
📈 Build at Scale – Design and improve high-availability backend services used by customers globally.
🤝 Mentor & Elevate – Share your knowledge, support teammates, and help raise the engineering bar.
🌍 Flexibility – Hybrid work with a healthy balance between office collaboration and focused work.
💰 Competitive Compensation – We invest in experienced engineers who create impact.
🏖️ Extra Time Off – Because great engineering also requires time to recharge.
🩺 Private Health Plan – We've got your back.
✈️ Travel Budget – Explore, learn, and recharge.
📚 Continuous Learning – Conferences, courses, books—we'll support your growth.
🎉 A Team You'll Actually Enjoy Working With – Smart people, low ego, high ownership.
Designing and building scalable backend services for a global communication platform.
Driving architectural decisions and continuously improving our systems.
Collaborating closely with Product, Design, QA, and Engineering.
Mentoring other developers through code reviews, technical discussions, and everyday collaboration.
Taking ownership from idea → architecture → production → continuous improvement.
Extensive professional experience building backend systems with Java.
Strong understanding of distributed systems, APIs, databases, and scalable architectures.
Experience with Docker, AWS, and MySQL.
Experience working with production systems, monitoring, and operational ownership.
Ability to mentor others and lead technical discussions while remaining hands-on.
Strong product mindset—you care about solving user problems, not just implementing tickets.
Curiosity, ownership, and a desire to continuously improve.
👉 If you're looking for a place where your experience truly matters and where you'll have the opportunity to influence both the product and the people around you, we'd love to meet you.
Send us your CV 📩 and let's build what's next—together.
Skills Required
- Extensive professional experience building backend systems with Java
- Strong understanding of distributed systems, APIs, databases, and scalable architectures
- Experience with Docker, AWS, and MySQL
- Experience with production systems, monitoring, and operational ownership
- Ability to mentor other developers and lead technical discussions while remaining hands-on
- Strong product mindset focused on solving user problems
- Curiosity, ownership, and desire to continuously improve
What We Do
Onoff is a French telecommunications company that provides cloud-based mobile telephony through smartphone and web applications. Its services let individuals and businesses use multiple mobile numbers without additional SIM cards or phones, while Onoff Business enables employers to assign and manage numbers, calls, SMS, contacts, voicemail, reporting, and integrations for teams. The company combines mobile-app and cloud technologies to make communications more flexible, economical, and environmentally friendly.
