Client Engineering Lead

About Tandem

Tandem is the leading global language learning community, where 10 million members in over 180 countries practice languages together. The concept of learning from each other is not only an integral part of the Tandem community but it is also at the heart of our everyday lives at Tandem. This shared connection through learning helps us to grow and enhances the language journeys of our members.

We are based in Berlin and are backed by top European investors. We are highly international and driven by a shared passion for languages, technology, and culture. Together, we are on a mission to build a product that not only teaches a new skill but also encourages meaningful cross-cultural conversations.

Your role will be to:

As our Client Engineering Lead, you will be the guardian of our Android and iOS ecosystems. You will balance your time between mentoring a talented team of five engineers and remaining hands-on with the code to ensure our mobile applications meet the highest industry standards.

We have recently adopted Kotlin Multiplatform (KMP). You will play a pivotal role in defining the target architecture between our backend, KMP business logic, and the native clients. We are looking for a leader who possesses a deep understanding of both iOS and Android, and who can pragmatically refactor codebases to drive tangible business value.

Reporting to the CTO, you will act as the bridge between business goals and technical execution - leading sprint refinements, ensuring delivery excellence, and championing the integration of AI across our engineering workflows.

You are the right fit for the role if you:

• 5+ years of professional experience in Swift/iOS development.
• 5+ years of professional experience in Kotlin/Android development.
• A mastery of Clean Architecture and SOLID principles.

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• Extensive experience in Unit Testing and designing for testability (ideally through TDD).
• Experience scaling large-scale applications (100,000+ active users) with significant technical complexity.
• A history of collaborating closely with Marketing and Growth functions.
• The confidence to be the "mobile expert in the room," with the ability to both drive and constructively critique technical designs.
  
  

What will make you stand out:

• Hands-on experience with Kotlin Multiplatform (KMP).
• Experience building and scaling real-time chat services.
• Expertise in handling real-time media (audio/video streaming).
• A proven track record in iterative design within agile, cross-functional teams.
  
  

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The Benefits

Passion for languages:

We’re a team of 30 people speaking 20 languages fluently between us. For those wanting to improve their German (or Denglisch!), you can join one of our German classes on us.

Take a deep dive:

As a Tandem team member, we’ll give you a budget for up to 6 “Deep Dive Days” per year. Pick a topic you’ve always wanted to explore for your professional development that has never made it out of your backlog. Then book a cabin in the woods or whatever matches your individual learning style.

Teams who train together, stay together:

We offer Urban Sports Club gym memberships to boost our team’s physical and mental health. If you prefer, we can contribute to your monthly public transport ticket instead.

It takes a team to Tandem:

Bonding with our teammates outside of our normal work routine is important to us. We organize regular team events: from day trips to monthly lunches, summer BBQs, and movie nights.

Balance matters:

Life isn’t just about work. We know when to snooze Slack notifications, recharge our batteries, and take time out for our personal hobbies. As home office has become the new normal for some of us, it’s even more important to be able to switch off from work and relax.

Modern family:

As part of our family-friendly company philosophy, we embrace flexible working hours, welcome families to our events, and love for our kids to visit the office and get a taste of life at Tandem.

Relocation without the stress:

If you’re looking to relocate to Berlin, we’re ready to assist you with the infamous German bureaucracy. Many of us have been through it before, so we have plenty of tips to share. You’ll feel settled in no time.

Hybrid by design:

We’re all about embracing a flexible, modern way of working. That’s why we focus on a hybrid approach—balancing time between our vibrant Berlin-Mitte office and the comfort of your home. It’s the best of both worlds, and we’ll support you in creating the perfect setup for this dynamic way of working.

About Us

Tandem is the leading global language learning app, where 30 million members in over 200 countries practice languages together. The concept of learning from each other is not only an integral part of the Tandem community but is also at the heart of our everyday lives at Tandem. This shared connection through learning helps us to grow and enhances the language journeys of our members.

We are based in Berlin and are backed by top European investors. We are highly international and driven by a shared passion for languages, technology, and culture. Together, we are on a mission to build a product that not only teaches a new skill but also encourages meaningful cross-cultural conversations.