Machine Learning Engineer, Search ML

Job Overview

Machine Learning Engineer, Search ML- Mercari
Employment Status: Full-time
Work Hours: Full Flextime (no core time)
Office: Roppongi

Key Responsibilities

• Elevate the Buyer Journey: Drive the optimization of item search and discovery capabilities at Mercari; take end-to-end ownership of core search business logic and user experience design.


• Architect Next-Gen AI Models: Design and deploy state-of-the-art machine learning models and robust training pipelines (incorporating Hybrid Search, Learning-to-Rank, Agentic Shopping, etc.) while continuously enhancing system reproducibility and debuggability.


• Standardize Experimentation Frameworks: Spearhead the development of standardized evaluation and experimentation infrastructure—including offline evaluation frameworks, online A/B testing guardrails, monitoring dashboards, and alerting systems—to accelerate iteration cycles and mitigate regressions.


• Drive Cross-Functional Alignment: Partner seamlessly with infrastructure, product, and adjacent engineering teams to align on scalability, latency, reliability, and cost efficiency, while orchestrating complex, cross-service architectural changes.

Required Qualifications

• Experience: 3+ years of professional experience in Machine Learning or Search Engineering.


• Search Expertise: Proven track record of optimizing end-to-end search experiences using data-driven methodologies (e.g., hybrid retrieval, learning-to-rank, embedding-based search, and advanced evaluation metrics).


• Production Engineering: Hands-on experience with production-grade ML/Search serving infrastructure, including one or more of the following: online inference services, feature stores, embedding spaces, evaluation/experimentation tooling, or offline indexing pipelines.


• Soft Skills: Strong collaborative and communication skills, with a demonstrated ability to align diverse technical teams and cross-functional stakeholders.

About Mercari

About Mercari
Circulate all forms of value to unleash the potential in all people
\"What can I do to help society thrive with the finite resources we have?\" The Mercari marketplace app was born in 2013 out of this thought by our founder Shintaro Yamada as he traveled the world. We believe that by circulating all forms of value, not just physical things and money, we can create opportunities for anyone to realize their dreams and contribute to society and the people around them. Mercari aims to use technology to connect people all over the world and create a world where anyone can unleash their potential. For more information about Mercari Group's mission, see Mercari's Culture Doc