Senior/Staff Machine Learning Engineer at River

At River we are building the world’s most trusted financial institution to empower people to take ownership of their financial lives through Bitcoin, the world’s only incorruptible digital money. We believe in a future where every person will have bitcoin savings, and every business will have bitcoin on the balance sheet. We obsessively design and build delightful products that help our clients buy, sell, secure, and use Bitcoin. We are looking for a Senior/Staff Machine Learning Engineer to build and own machine learning-driven systems that power automation and decision-making across onboarding, risk, compliance, and operations. You will apply ML and LLMs in production to solve real-world problems. Our core stack includes XGBoost, PyTorch, Python, MLflow, Postgres, and BigQuery. River is growing quickly and has raised more than $50 million from leading investors, including Goldcrest, Kingsway, Polychain, M13, DG, and Valor. We have also released our company's financials [Upgrade to PRO to see link] and proof of reserves [Upgrade to PRO to see link] publicly, so all of our clients and employees can verify the robustness and growth of the business themselves. WHAT YOU WILL BE DOING - Design, build, and iterate on machine learning models and LLM-based systems that power critical decisions across fraud, compliance, growth, and operations - Work with messy, real-world data to identify signals, build features, and continuously improve model performance - Make practical tradeoffs between model performance, interpretability, and operational cost - Partner closely with product and operations to identify and solve problems that directly impact experience of hundreds of thousands of clients - Contribute to backend systems and data pipelines that support model training and inference (without being primarily an infrastructure role) - Write high-quality, tested code and participate in code reviews - Take long-term ownership of critical systems as River scales WHAT WE LOOK FOR IN YOU - 4+ years of experience building and applying machine learning models in real-world settings, or comparable research experience - Strong intuition for ML concepts and how they apply in practice (i.e., tradeoffs) - Experience working on problems involving noisy, imbalanced, or real-world data - You take ownership of systems and are comfortable solving ambiguous problems - You have strong judgment around correctness, reliability, and operational risk - You can translate between technical systems and business/product needs - You're excited about what we are building at River NICE TO HAVES - Experience in fraud/risk, fintech, or other high-signal/noise domains - Experience with tabular ML and feature engineering-heavy workflows - Familiarity with LLM-based systems or applied AI use cases - You have worked at a rapidly scaling company - Interest in Bitcoin LOCATION & SALARY - 100% remote option available within the Americas and Europe, with offices in SF, NYC, and Columbus - Salary range between $150,000 - $250,000 based on skills and experience - Significant equity stock options - Medical, Dental and Vision Benefits - Unlimited PTO - Parental Leave separate from regular PTO policy - 401k