Product Engineer/プロダクトエンジニア, Backend (New Business) - Mercari Marketplace

JD in Japanese follows. 英文の後に和文JDをご覧いただけます。

Product Engineer/プロダクトエンジニア, Backend (New Business) - Mercari Marketplace

• Employment Type: Full-time
• Work Hours: Flextime system (no core hours)
• Office: Roppongi

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

About Mercari Group

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 globe and create a world where anyone can unleash their potential. You can learn more about our mission on the Culture page of our Careers site.

Organization/Team Mission

Mercari Engineering Principles

The Mercari Engineering Principles articulate the shared beliefs and behavioral foundations of Mercari’s engineering organization. They are designed to complement—from an engineering perspective—the mission, values, and culture shared by all Mercari members. These principles ultimately help us achieve Mercari’s mission by defining the ideal state that we seek to realize in the long term.

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

For more details, see the Culture page of our Mercari Engineering Portal.

This team builds emerging marketplace domains that will become Mercari’s next growth pillars, including cross-border and new commerce experiences. You will collaborate across Mercari and/or with external partners to turn early hypotheses into scalable products—leveraging the strengths of our existing marketplace while laying the foundation for the next stage of global growth and enabling a safe, global marketplace where sellers and buyers worldwide can transact with confidence.

Under a development structure built around AI, we aim to maximize both the value we deliver to users and the speed at which we deliver it. As a Product Engineer at Mercari, you will take end-to-end ownership from spec definition through delivery. We are looking for someone willing to go beyond their role to solve problems, rather than staying confined to their own area of expertise. You will be expected to proactively get involved from the definition phase, and to independently lead every step of the development process—shaping product specs, building consensus, establishing quality and measurement, releasing, and the operations that follow.

• To learn more about Mercari’s mission and values, see the Culture page of our Careers site.

Work Responsibilities

As a Product Engineer, you will take end-to-end ownership of spec definition through production release. Working closely with product managers and other stakeholders, you will finalize specs based on working prototypes and autonomously lead every step, including quality, measurement, release, and the operations that follow. Under a development structure built around AI, you will be responsible for delivering results in a way that balances both speed and quality, from start to finish.

Main Responsibilities

• Leading spec definition and implementation
• Start from a working prototype rather than waiting for perfect specs: build something first, then update and finalize the specs based on observed behavior, and lead implementation across platforms

• Leading quality, measurement, and release phases
• Establish reliable measurement through event design, logging, and dashboards, while also designing quality standards and phased rollout plans

• Making technical design decisions autonomously
• Independently make decisions on architecture, APIs, data design, security, and operational considerations, explaining trade-offs in a business context to drive progress

Tools and Technologies Used

• You will have access to a range of tools centered around Claude
• We regularly expand and update our selection of models and tools in line with team needs and industry trends
• For more information, see the Technology Stack page of our Engineering portal

Qualifications

• Required Experience/Skills
• Shared belief in the mission and values of Mercari Group and its various companies
• Ability to take end-to-end ownership: personally leading not just implementation, but spec definition and consensus-building, and staying accountable through production release and maintenance
• Ability to leverage AI in development while balancing speed and quality
• Ability to use AI coding tools like Claude Code effectively in day-to-day work, while evaluating, correcting, and integrating AI output rather than taking it at face value
• Ability to build prototypes quickly and finalize specs based on these working prototypes

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• Ability to make technical design decisions autonomously (architecture, APIs, data, security, operations, etc.) and explain trade-offs in a business context
• Willingness to cross into other domains (backend, frontend, iOS, Android, QA, etc.) and adjacent roles, with the ability to get started on your own in unfamiliar areas by leveraging AI and documentation
• Willingness to mentor and coach others with a motivation to help the organization grow

• Preferred Experience/Skills
• Experience delivering results from ambiguous specs: prototyping, refining and finalizing the specs, and seeing the project through to delivery
• Experience with measurement design (events/logs), dashboard development, phased rollouts, and making go/no-go release decisions
• Experience working alongside product managers to finalize specs, unblocking decisions when they get stuck
• [ FILL IN: Add any other preferred experience/skills in the relevant domain (C2C Marketplace, Commerce, Logistics, Fintech, etc.)]
• Experience using English professionally, or experience developing products in a multinational team

• Language Requirements
• Japanese: Proficient (CEFR - B2) required
• English: Independent (CEFR - B1) preferred
• For details about CEFR, see the Language page of our Careers site.

Learn More About Mercari Group

• Careers site: https://careers.mercari.com/en/
• Mercan: https://careers.mercari.com/en/mercan/
• Social media: X / LinkedIn

Recruiting at Mercari

At Mercari Group, we place great importance on connecting with and embodying our mission and values. In order to build an organization where every member can contribute at their full potential, we try to understand the experience and skills of each candidate as accurately as possible.

Selection process at Mercari Group (may vary by team)

• Document screening
• Skills test
• Interviews: multiple rounds, depending on the position
• Reference check: completed online (conducted before or after the final interview)
• Offer: decided based on the results of the final interview and reference check

For more details about our selection process, see the Recruitment & Selection page of our Careers site.

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 .

Before submitting your application, please read and acknowledge our Privacy Policy .

Product Engineer/プロダクトエンジニア, Backend (New Business) - Mercari Marketplace

• 雇用形態：正社員
• 働き方：フレックスタイム制（コアタイムなし）
• 勤務地：六本木

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