Freelance Senior Backend Engineer (all genders)

Role overview

A small, AI-first engineering group is rebuilding the architecture behind an online language learning platform, and this freelance role puts you among the senior engineers laying that foundation. You will design, build, ship, and operate the services that create, store, and serve learning content, owning them end-to-end on a serverless TypeScript and Node stack on AWS. It is a hands-on individual-contributor position where seniority shows up in the decisions you own rather than in a reporting line.

Responsibilities

- Build and evolve services across the learning platform, owning each one from its API contract through to its behaviour in production. - Take on services you did not write, working alongside the engineers who originally built them. - Design durable API and data contracts, including type-safe transforms at the boundaries between API, domain, and persistence. - Run what you ship: instrument it, understand how it fails, change live data safely, and lead incident analysis on systems you own. - Use coding agents as part of daily delivery, reviewing their output carefully before relying on it.

Requirements

- Strong, hands-on backend engineering in TypeScript and Node as your primary working language today (true back-end services, not build tooling or front-end server wrappers). - Deep AWS experience in a serverless-first setting, designing against Lambda, API Gateway, DynamoDB, and event streaming rather than only deploying onto them. - Ability to design API and data contracts and model a domain, with type-safe boundary transforms. - Real production ownership: instrumenting your own services, handling incidents, and changing live data without losing any. - Practical, daily use of coding agents combined with rigorous verification of what they produce. - Self-sufficiency in unfamiliar codebases, plus working familiarity with Terraform and CI/CD pipelines. - Python as a welcome secondary language for the occasional Python service.

Nice to have

- Go or Rust for performance-critical components (fully optional). - Experience with monorepo build systems and shared tooling. - Public technical work such as open-source contributions or writing.

Benefits and work setup

- Remote role, with Berlin-friendly working arrangements. - Short interview process: an initial screen followed by one working session with the hiring manager. - Flexible working models, learning budgets, and free access to the language learning platform. - Mission-driven product with global reach, focused on responsible use of AI in education. - Small, fast-moving team with a structured delivery approach and a collaborative product, engineering, and language-learning community.