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Rebtel is a profitable, 20-year-old company connecting people across borders, now pivoting AI to the core of its operations. As Senior Machine Learning Engineer, you'll define how AI is done at Rebtel—standardizing tooling, evaluating models in production, and establishing best practices for prompts and pipelines. You'll report to the Head of Data and partner with one other ML/AI engineer to build classical ML for business operations and LLM-powered systems for the product.
You'll own two complementary tracks: (1) Classical ML in production for operational leverage—building risk and fraud models across payments and account behavior, churn prediction on a million-plus user base, forecasting, pricing, and segmentation. You'll scope models with stakeholders, build, deploy, monitor, and retrain end-to-end. (2) LLMs and AI agents—starting with customer support RAG pipelines, prompt orchestration, and evaluation harnesses, then moving LLM capability into user-facing product features. You'll guide the company on where AI creates real leverage, what to build versus buy, and ship systems that matter.
Required: 5+ years hands-on ML engineering in Python with real production ownership (not notebooks). Strong fundamentals in classical ML—feature engineering, model selection, validation, and keeping models healthy in production. Genuine production mindset: monitoring, retraining, eval harnesses, CI/CD for models, debugging at 2am. Comfort working the full loop from stakeholder scoping through data, model, deployment, measurement, and iteration. Fluent English, ability to translate business problems to ML ones. Hands-on LLM frameworks (LangChain, LangGraph, LlamaIndex). Built RAG systems, agentic workflows, or LLM products used by real users or teams. Comfortable with vector databases, embeddings, prompt evaluation, and rigorous LLM measurement. Obsessed with staying current on AI developments. Experience with major cloud (AWS/GCP/Azure), containers, and modern data stack. MLOps tooling (MLflow, Airflow, Kubernetes, feature stores) is a plus. Fintech, payments, telecom, or regulated/operational domain background is a plus.
Rebtel is based in Stockholm with a diverse, international team. The company values speed, ownership, and real impact with minimal process overhead. Benefits include pension, health checkups, dental and occupational insurance, wellness allowance (5,000 SEK), gym discounts, bonus program, extra parental pay, 30 days vacation, and relocation support.
