Freelance Senior Backend Engineer

Who you are

• 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
• 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
• 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

What the job involves

• 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
• 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

Benefits

• 30 vacation days and flexible working hours
• BVG card or Swapfiets bike
• Jobbatical and Sabbatical options
• Many internal & external learning opportunities to choose from
• A yearly Learning & Development budget
• Visa and relocation assistance
• Full access to Babbel & Babbel Live classes
• Modern office in the heart of buzzing Berlin equipped with a family, music, faith and nap room
• Various internal communities to be part of including the Femgineers, DEI Ambassadors, Accessibility & Disability Group and more