Senior Machine Learning Scientist (AI)

TL;DR

Senior Machine Learning Scientist (ML/AI): Developing and optimizing ML models for a fitness social marketplace with an accent on ranking, recommendation systems, and LLM agents. Focus on improving event discovery, predicting churn, and building agentic systems like HostCopilot.

Location: Remote (Europe / EU timezone)

Company

hirify.global is a community-first fitness platform turning workouts into social experiences, backed by a16z speedrun and other prominent investors.

What you will do

• Frame fuzzy product problems as ML tasks using ranking, retrieval, classification, or LLM agents.
• Manage the full ML lifecycle: from data exploration and offline evaluation to production deployment and monitoring.
• Develop LLM-powered features for HostCopilot (retention nudges, pricing suggestions) and AI Concierge services.
• Build agentic systems incorporating RAG, tool use, structured outputs, and human-in-the-loop evaluation loops.
• Partner with product and growth teams to measure marketplace impact rigorously via A/B testing.
• Set the bar for ML rigor regarding experiment design, offline metrics (NDCG, AUC), and technical writeups.

Requirements

• 5+ years of applied ML experience shipping models to production.
• Strong proficiency in Python and SQL for writing production-grade code.
• Solid foundations in ranking and recommendation systems, NLP, classical ML, or causal inference.
• Experience with modern LLM tooling, including prompting and RAG.
• Must be based in the Europe / EU timezone.
• Advanced degree in ML, CS, or stats (PhD or research background is a strong bonus).

Nice to have

• Experience working with marketplaces, search, or recommendation systems.
• Familiarity with the tech stack: FastAPI, PostgreSQL, BigQuery, FAISS, sentence-transformers, and AWS.

Culture & Benefits

• Remote-first and async-friendly work environment.
• Competitive salary and early-stage equity.
• AI-native culture with daily use of tools like Claude Code and Cursor.
• High-ownership role where you define the ML roadmap.
• Culture of diversity of thought, leadership at all levels, and high quality baselines.