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 transitioning from third-party APIs to self-hosted models, optimizing production performance, and driving end-to-end ML solutions from discovery to deployment.

Location: Must be based in or able to work from Tartu, Estonia (Hybrid: 3 days/week in office)

Company

Bolt is a leading European tech company providing mobility and delivery services to over 200 million customers across 50+ countries.

What you will do

• Design, train, and deploy ML/LLM models for catalogue enrichment, moderation, and categorisation.
• Drive the transition from frontier API models to fine-tuned open-weight models by building curation and training pipelines.
• Develop agentic AI systems for multi-step catalogue workflows, including tool use and guardrails.
• Build robust evaluation infrastructure, including offline benchmarks, regression suites, and LLM-as-judge pipelines.
• Own the serving and cost optimization for self-hosted models, including throughput tuning and GPU utilization.
• Collaborate cross-functionally with software engineers, product managers, and data scientists to productionise ML solutions.

Requirements

• Must be based in or able to work from Tartu, Estonia
• Proven experience building and shipping ML systems in production at scale.
• Demonstrated track record taking LLM-based systems to production, including evaluation and cost management.
• Hands-on experience fine-tuning and serving open-weight models (e.g., LoRA/QLoRA, SFT).
• Deep expertise in NLP or recommendation systems with measurable business impact.
• Mastery of Python, SQL, and production experience with deep learning frameworks like PyTorch or TensorFlow.

Culture & Benefits

• Direct impact on the future of mobility and delivery for millions of users.
• Fast-moving, autonomous team environment with supportive colleagues.
• Competitive salary and stock option package.
• Wellness perks focused on physical and mental health.
• Hybrid working model with 3 days in the office to foster team connection.