Freelance Senior Backend Engineer (all genders)

About Babbel Labs

Babbel Labs is building the future of language learning. We are an AI-first, independent company within the Babbel group, based in Berlin. Our teams bring AI, research and product together to ship experiences that set a new standard for how people learn.

The role

Babbel Labs is rebuilding how learning content is created, stored and served, and how we decide what a learner sees next. The architecture for that is being set now, by a small number of engineers, and this role is one of them.

You will build and run the services behind it, in a serverless-first TypeScript and Node stack on AWS, owning them from the contract at their edge to their behaviour under load.

This is a senior individual-contributor role. You will design, build, ship and operate, and the seniority shows in the decisions you own rather than in a team reporting to you.

How you'll make an impact

Build and evolve services across our learning platform, owning each one from its API contract through to what runs in production.

Take on services you did not write, alongside the people who did.

Design API and data contracts that hold up over time, with type-safe transforms between the API, the domain and persistence.

Run what you build. Instrument it, know how it fails, change live data safely, and be the person who works out why it broke.

Deliver with coding agents as a matter of course, and verify what they produce before you rely on it.

Your skills and qualifications

Strong, hands-on backend engineering in TypeScript and Node as your primary working language today. We mean back-end services: not build tooling, and not the server a front-end framework happens to ship with.

Deep, practical AWS experience in a serverless-first setting. Lambda, API Gateway, DynamoDB and event streaming are our daily tools, and we want someone who has designed against them rather than only deployed onto them.

The ability to design API and data contracts and to model a domain, including type-safe transforms at the boundaries between the API, the domain and persistence.

Real production ownership. You have instrumented your own services, understood their failure modes, changed live data without losing any, and worked incidents on systems you owned.

Coding agents are part of your daily workflow, and you check their output before you rely on it. You are neither dismissive of them nor careless with them.

Self-sufficiency. You get yourself unstuck in an unfamiliar codebase without a minder, and you work within its grain rather than rewriting what you have not yet understood.

Working familiarity with infrastructure as code (Terraform) and CI/CD pipelines, enough to ship and change your own service's delivery. This is not an infrastructure role, so depth here is not the bar.

Python as a welcome secondary language. Some of our services are Python, and a Labs engineer can expect to touch them.

Nice to have

Go or Rust for performance-critical components. Fully optional.

Experience with a monorepo build system and shared tooling.

Public technical work, such as open-source contributions or writing.

Ways of working

This is a hands-on individual-contributor role on a small team that moves fast, agent-first, but with a structured and disciplined delivery approach. It is remote and Berlin-friendly. The interview process is deliberately short: an initial screen, followed by one working session with the hiring manager.

Why Join Babbel Labs

Work on a mission-driven product with global impact.

Shape how AI is used responsibly in education.

Collaborate with experienced product, engineering, and language experts.

Flexible working models, learning budgets, and free language learning.

An inclusive, supportive environment that values curiosity and growth.

Diversity at Babbel

As part of our ongoing journey towards building a diverse, equitable and inclusive company, we welcome everyone to apply, especially those individuals who are underrepresented in tech. We are a learning company, inside and out, and we encourage you to apply even if you do not fit all the technical requirements - all candidates are assessed based on skills, qualifications and on our business needs. Please state your pronouns in your application, and let us know if you’d like to be addressed by a name other than the one appearing on your official documents. If you have a disability or special need, feel welcome to inform us, so that we can provide you with the proper assistance in the application process.