Senior Machine Learning Engineer – Babbel Labs

Stack

Responsibilities

• ▹Work with the Principal Scientist to take designs from spec into production, then keep improving them on your own judgement
• ▹Help shape new features from the beginning, not just implement a spec
• ▹Own core personalisation and mastery-tracking subsystems end to end
• ▹Design the evaluation: a rigorous offline benchmark against a real baseline and the online experiment that confirms or kills a change
• ▹Run what you build: instrument it and fix silent failures before they become incidents
• ▹Deliver with coding agents as a matter of course and verify their output

Requirements

• ▹Strong, hands-on ML engineering that has shipped real models to production (recommendation, ranking, scoring or trust-and-safety systems under real user load)
• ▹Experience with probabilistic modelling, latent-variable modelling and Bayesian inference, or equivalent rigour from an adjacent domain
• ▹ML system evaluation: monitoring metrics you define, debugging odd output, rolling out changes to a live scoring or ranking system
• ▹Rigorous experimentation: benchmarking against a real baseline, running and reading A/B tests correctly
• ▹TypeScript/Python as primary languages, with enough command of the surrounding stack (AWS, Terraform, CI/CD) to ship and own your service's delivery
• ▹Coding agents as part of the daily workflow, with checked output

Nice to have

• ▹Experience with psychometric models such as Item Response Theory
• ▹Graph ML experience (embeddings, graph neural networks, relational modelling) at real scale
• ▹Public technical work: open-source contributions, writing or competitive ML

Soft skills

What we offer

• ▹Remote and Berlin-friendly
• ▹Small, fast-moving, agent-first team with disciplined delivery
• ▹Short interview process: an initial screen and one structured working session with the hiring manager

About the company

Babbel Labs is an AI-first, independent company within the Babbel group, based in Berlin, building the future of language learning. Its teams bring AI, research and product together.