Senior Machine Learning Engineer (AI)

TL;DR

Senior Machine Learning Engineer (AI): Building and scaling AI systems for merchant catalogue automation with an accent on LLM-based enrichment, fine-tuning open-weight models, and agentic workflows. Focus on driving the transition from third-party APIs to self-hosted models, optimizing production performance, and building robust evaluation infrastructure.

Location: Hybrid (Bucharest, Romania). Requires a minimum of 3 days in the office each week.

Company

Bolt is a fast-growing European tech company focused on mobility and delivery, serving over 200 million customers across 50+ countries.

What you will do

• Design, train, and deploy ML/LLM models for catalogue enrichment and moderation at scale.
• Drive the transition from frontier API models to fine-tuned open-weight models.
• Build agentic AI systems for multi-step catalogue automation workflows.
• Develop evaluation and experimentation infrastructure, including offline benchmarks and A/B testing.
• Own the serving, cost, and performance optimization for self-hosted models.
• Collaborate cross-functionally to productionise and monitor ML solutions.

Requirements

• Proven experience building and shipping ML systems in production at scale.
• Demonstrated track record taking LLM-based systems to production.
• Hands-on experience fine-tuning and serving open-weight models.
• Deep expertise in NLP or recommendation systems.
• Mastery of Python and SQL with production experience in deep learning frameworks.
• Strong product sense and ability to drive ambiguous problems to measurable impact.

Culture & Benefits

• Direct role in shaping the future of mobility and delivery.
• Impact on millions of customers and partners globally.
• Fast-moving, autonomous team environment.
• Competitive salary and stock option package.
• Wellness perks for physical and mental health.
• Hybrid working model with a focus on team connection.