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Software Engineer, Search - US App

• Employment Status: Full-time employee
• Work Hours: Full Flextime (no core time)
• Office: Roppongi

For more details, see the Overview of Our Positions section on our Careers site.

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.

Organization/Team Mission

Mercari Engineering Principles

Mercari Engineering Principles are a shared understanding that serves as the foundation of engineering beliefs and behavior at Mercari. The Engineering Principles are designed to complement the organizational identity (Mercari's mission, values, and culture) from an engineering viewpoint.

These principles ultimately help us achieve Mercari's mission by defining the ideal state we seek to realize in the long term:

• Passion For The Product
• Grow Together
• Solve Through Mechanisms
• Collaborate Openly

For more details, please see the following link:

• Engineering Culture

Our team's mission is to help buyers discover the most relevant items and empower sellers by improving their visibility in Mercari's US marketplace. We strive to provide a fast, trustworthy, and effective search experience that connects millions of users with what they're looking for, seamlessly and at scale.

The Search team is responsible for the end-to-end development and operation of the search system, including relevance tuning, query understanding, and infrastructure reliability. Built on Elasticsearch, our system handles high query volumes and constantly evolving inventory with stability, freshness, and cost efficiency.

Recent or ongoing initiatives include:

• Modernizing our ranking and retrieval pipeline to improve conversion, engagement, and search precision

• Strengthening platform stability and flexibility through real-time indexing, cache optimization, search traffic resilience, and observability tooling

• Collaborating with product, backend, and infrastructure teams across the US and Japan to build a world-class search experience

See here for more information about our mission and values.

Work Responsibilities

• Own the end-to-end search delivery cycle: independently identify improvement opportunities through log, user signal and metric analysis; define and track KPIs; and ship iterations that improve relevance and conversion while aligning with product and business goals.
• Design, develop, and maintain Mercari US's search infrastructure and backend microservices.
• Build and optimize search indices, ranking algorithms, and query pipelines focused on relevance, retrieval efficiency, and low latency.
• Design and implement gRPC and RESTful endpoints for inter-service and client communication.
• Enhance system scalability, performance, and reliability by designing reusable components and shared libraries such as indexing and query-parsing utilities, optimizing caching, databases, and load balancing, and enforcing comprehensive automated tests with robust monitoring and observability
• Mentor junior engineers, lead code reviews, and actively contribute to architectural decisions and technical documentation.
• Collaborate with cross-functional teams including product, infrastructure, and QA to deliver high-impact features and improvements.

Unique Challenges

• Search is a core function at Mercari, connecting millions of buyers and sellers. You will own the continuous improvement cycle for Mercari search, analysing metrics, proposing experiments, and delivering enhancements that provide highly relevant, fast, and reliable search experiences to meet diverse customer needs.
• Collaborate closely with product managers, backend engineers, and machine learning specialists to design advanced, end-to-end systems.
• Architect and implement highly scalable services to support the continued growth of Mercari US's user base and product offerings.
• Contribute proactively to Mercari's engineering culture by sharing ideas, driving improvements, and mentoring peers.
• Develop a deep understanding of the US market to ensure product decisions align with customer expectations and business goals.
• Work in a globally distributed team, collaborating with teammates in both Tokyo and the US, to deliver impactful solutions across time zones and cultures.

Qualifications

• Required Experience/Skills

• Strong hands-on experience with search technologies such as Elasticsearch, OpenSearch, or Solr, including schema design, relevance tuning, and query optimization.

• Ability to independently analyze search metrics and ship measurable improvements in production systems.
• Bachelor's degree in Computer Science, Software Engineering, or a related field (or equivalent practical experience).
• 5+ years of professional experience developing and operating search engines and/or backend services in high-traffic production environments.
• Experience building and operating microservices at scale, including containerization (Docker, Kubernetes), CI/CD and Infrastructure as Code (Terraform), observability (Prometheus, Grafana), and optimization of databases, caching, concurrency, and search relevance/latency
• Strong programming expertise in Java or Go; familiarity with Python or PHP is a plus.
• Excellent English communication skills, with the ability to collaborate effectively across functions and regions.

• Demonstrated ability to mentor and guide junior engineers.

• Preferred Experience/Skills

• Experience with vector search or semantic search frameworks.

• Domain knowledge of marketplace or e‑commerce platforms.
• Experience deploying and scaling services on major cloud platforms such as Google Cloud Platform (GCP), AWS, or Azure.
• Familiarity with message queues and event-driven architectures (e.g., Pub/Sub, Kafka).
• Contributions to open-source projects, especially in search or backend domains; or public technical engagement through blogs, talks, or conferences.

• Experience working within large, cross-functional and geographically distributed teams.

• Language

• English: Business level (CEFR B2 or higher) required

• Japanese: Basic (CEFR - A2) optional
• For details about CEFR, see here.

Learn More About Mercari Group

• Careers site:
• Mercan:
• Social media: X / Linkedin

Recruiting at Mercari

At Mercari Group, we value empathizing with and embodying the mission and values ​​of the Group and each company. To promote the creation of an organization that maximizes the total amount of value exhibited by all members, we would like to understand the experience and skills of each candidate as accurately as possible.

Recruiting cycle at Mercari Group

• Application screening
• Skill assessment: For engineering positions, you will be asked to complete a skill assessment on HackerRank or GitHub. For non-engineering positions, you may be asked to complete an assessment depending on the position. (The timing of the assessment may coincide with the interview process.)
• Interview: The number of interviews may vary depending on the position.
• Reference check: We will ask for online references around the timing of the final interview.
• Offer: Offers will be determined carefully in consideration of the final interview and the reference check.

Learn more about our recruiting process here.

Equal Opportunity Hiring

Here at Mercari, we work to realize a world in which no one's potential is limited by their background and everyone has the opportunity to freely create value. We also firmly believe that a mindset of Inclusion & Diversity is essential for us to achieve our mission.

This, of course, extends to our hiring practices as well. Mercari is committed to eliminating discrimination based on age, gender, sexual orientation, race, religion, physical disability, and other such factors so that anyone who shares our mission and values can join us, regardless of their background. For more details, please read our I&D statement.

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