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Senior Software engineer, Android (AI/LLM) - Mercari

• Employment Status: Full-time
• 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

The AI / LLM Team's mission is focused on two core pillars, "building" and "enabling", delivering new AI-driven features and user experiences to maximize product-facing impact for Mercari's business. We do this both through independent initiatives owned by our team, as well as by horizontally collaborating with product and engineering teams across the entire organization.

As a senior Android engineer, you will lead complex product and technical initiatives, collaborating closely with ML engineers, backend teams, infrastructure specialists, designers, and product managers. You will drive architecture design, ensure technical excellence across Android codebases, and influence cross-team decisions to shape Mercari's next generation of AI-driven mobile experiences.

See here for more information about our mission and values.

Work Responsibilities

• Lead the design, implementation, and maintenance of high-quality Android features using Kotlin and modern Android frameworks.
• Drive end-to-end feature development, from requirement clarification through architecture design, implementation, testing, release, and post-launch improvements.
• Partner with backend, machine learning, infrastructure, and design teams to deliver seamless and scalable user experiences.
• Influence and improve Mercari's mobile platform, shared modules, and internal SDKs through strong architectural thinking and technical leadership.
• Establish best practices in code quality, testing, CI/CD workflows, and documentation across the Android organization.
• Champion engineering best practices and contribute to guidelines and standards across Client Engineering.
• Lead and contribute to cross-team initiatives, fostering alignment and consistency across Client Engineering.
• Identify, analyze, and resolve complex performance, stability, and maintainability challenges.
• Mentor junior and mid-level engineers, providing guidance on technical skills, design decisions, and career growth.
• Collaborate with iOS engineering leadership on design alignment and multi-platform product considerations.

Unique Challenges

• Architect and deliver AI-driven Android features leveraging Mercari Group's rich data assets and serving tens of millions of users.
• Navigate high-ambiguity problem spaces where user experience, product strategy, and ML constraints evolve rapidly.
• Define technical direction for high-performance, stable experiences in a fast-paced environment.
• Influence shared mobile foundations, advocating for scalable, resilient, and future-proof solutions.
• Balance innovation and speed with long-term platform stability and operational excellence.

Qualifications

• Required Experience/Skills

• Shared belief in Mercari Group's mission and values.

• Bachelor's degree in Computer Science, Engineering, or equivalent practical experience.
• Deep expertise in Kotlin and modern Android development (Jetpack, Compose, Architecture Components, Coroutines/Flow).
• Strong understanding of mobile architecture (MVVM, MVI, Clean Architecture, modularization strategies).
• Significant experience building, shipping, and maintaining production Android features at scale.
• Strong experience collaborating with backend/ML teams and integrating complex APIs.
• Ability to drive architecture discussions, lead technical decision-making, and manage ambiguity.
• Excellent communication skills with the ability to influence across teams.

• Passion for building polished, user-facing experiences and improving platform-wide quality.

• Preferred Experience/Skills

• Experience working on large-scale apps serving millions of users.

• Deep knowledge of performance optimization, instrumentation, crash analysis, and monitoring tools.
• Practical, production-level experience with Jetpack Compose and coroutine-based concurrency.
• Experience designing or contributing to shared modules, SDKs, or platform-level components.
• Familiarity with CI/CD for mobile, automated testing strategies, and release operations.
• Understanding of iOS fundamentals or cross-platform technologies (React Native, Flutter, KMM).

• Strong UI/UX sensibility and attention to detail.

• Language

• Japanese: Independent (CEFR B2) Optional

• English: Independent (CEFR B2) Required

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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