Senior Machine Learning Engineer: Search Quality

About us

Launched in 2019, Constructor is an AI-first ecommerce search and discovery platform that helps shoppers find the right products at the right time and enables leading global e-commerce brands to drive meaningful revenue and conversion gains.

As a Senior Machine Learning Engineer in the Search Quality team, you will improve the e-commerce experience for hundreds of millions of users across the world by building the systems that power relevance for global retailers - from fashion and grocery to electronics and hardware.

The mission is to measure search quality, push it higher, and catch degradations before the user does. You will achieve this through a blend of fine-tuned LLMs for relevance judgment, real-time models, and deep offline analysis of query logs.

About the Job

Your primary focus will be relevance evaluation and quality improvements:

• LLM-based evaluation. We fine-tune our own models to assess relevance. This involves teaching the model to understand query intent, represent items from messy catalog data, and align model judgments with real user behavior.
• Real-time quality in production. Reranking, filtering, signal computation. Latency is a strict requirement, so quality vs speed tradeoff is constant.
• Automated quality monitoring and agentic insights. Pipelines to detect degradations and find underperforming patterns. Agent-based systems that generate actionable recommendations for the product data and search configurations.

What makes this interesting

• Multi-domain, multi-language, at scale - 40+ languages, 20+ domains. The models need to generalize across all of them - without per-customer rules or overrides.
• No universal ground truth. A grocery retailer and a fashion retailer may have different perceptions on what "relevant" means.
• Efficiency at scale. Optimizing and scaling LLM inference across our entire customer base.

Requirements

• 4+ years shipping production ML systems
• Experience with search, information retrieval, or recommendation systems
• Hands-on experience with fine-tuning, evaluation frameworks, and scaling LLM deployments
• Strong Python and PyTorch. Fluency in SQL and data orchestration tools (Spark, Airflow)
• Experience designing and running A/B tests to validate model impact
• Excellent English communication skills
• Experience collaborating in cross-functional teams (ranking, product, data engineering)

Benefits

• 🧠 Work with smart and empathetic people who will help you grow and make a meaningful impact.
• 🎉 Regular team offsite events to connect and collaborate.
• 🌎 Fully remote team - choose where you live.
• 🏝️ Unlimited vacation time - we strongly encourage all of our employees take at least 3 weeks per year.
• 🛋️ Work from home stipend! We want you to have the resources you need to set up your home office.
• 💻 Apple laptops provided for new employees.
• 🧑‍🎓 Training and development budget for every employee, refreshed each year.
• 👪 Maternity & Paternity leave for qualified employees.
• 💵 Base salary: $80k–$120K USD, depending on knowledge, skills, experience, and interview results
• 📈 Stock options - offered in addition to the base salary