Lead Machine Learning Engineer (RecSys)

TL;DR

Lead Machine Learning Engineer (RecSys): Architecting and scaling recommendation and discovery engines for a social music app with an accent on scalable retrieval, ranking, and MLOps infrastructure. Focus on transforming user behavior into personalized real-time experiences and building robust evaluation frameworks.

Location: Hybrid in Warsaw, Poland

Company

hirify.global is a social music app in alpha stage building new ways for people to listen and respond through music via human-centric interactions.

What you will do

• Define the technical vision and architectural roadmap for recommendation and personalization engines.
• Design and implement scalable retrieval, ranking, and re-ranking pipelines for massive datasets.
• Lead the development of ML infrastructure, including feature stores and MLOps.
• Mentor and coach ML engineers to foster a culture of technical excellence.
• Implement offline evaluation frameworks and lead complex A/B testing strategies.
• Collaborate with Product and Engineering to align ML initiatives with business metrics.

Requirements

• Extensive experience scaling production-grade recommendation systems or ranking models.
• Deep knowledge of deep learning architectures and modern information retrieval methodologies.
• Proficiency with distributed data systems and frameworks like PyTorch or TensorFlow.
• Strong background in deploying low-latency models and drift monitoring.
• Demonstrated experience leading technical projects and mentoring engineers.
• Location: Must be based in or able to work hybrid in Warsaw, Poland

Nice to have

• Experience with streaming data and real-time/session-based recommendation systems.
• Domain expertise in audio processing or music streaming products.
• Familiarity with GNNs, reinforcement learning, or LLMs for recommendation context.

Culture & Benefits

• High autonomy and direct ownership over high-impact systems used by millions.
• Founding-stage equity through meaningful stock options.
• Ability to shape the broader engineering culture and hiring roadmap.
• Product-driven environment focused on collaborative innovation.
• 26 business days of paid time off per year plus additional days off and public holidays.