Freelance Senior Backend Engineer

Babbel Labs is rebuilding how learning content is created, stored and served, and how we decide what a learner sees next. 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 where you design, build, ship and operate.

What you'll do

• 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.

What you'll need

• Strong, hands-on backend engineering in TypeScript and Node as your primary working language today.
• Deep, practical AWS experience in a serverless-first setting. Lambda, API Gateway, DynamoDB and event streaming are your daily tools.
• 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.
• Self-sufficiency to get unstuck in an unfamiliar codebase without a minder.
• Working familiarity with infrastructure as code (Terraform) and CI/CD pipelines.

Nice to have

• Go or Rust for performance-critical components.
• Experience with a monorepo build system and shared tooling.
• Public technical work, such as open-source contributions or writing.
• Python as a secondary language.

What they offer

• Work on a mission-driven product with global impact in education.
• Shape how AI is used responsibly in education.
• Flexible working models and free language learning.
• Learning budgets and an inclusive, supportive environment.