Senior Software Engineer, Android (Mobile Enablement) - Mercari

Description

As a Mobile Enabler mainly focusing on the Android ecosystem, you will own and evolve the entire Android engineering ecosystem at Mercari, from lower-level platform capabilities to higher-level architectural decision-making, providing the best experience for our engineers and Mercari users.

Tech Stack:

• Android Development: Kotlin, Jetpack Compose, Kotlin Coroutines & Flow
• Build & Tooling: Gradle (Develocity), Android Studio
• API & Data: Protocol Buffers
• AI Tools: Claude Code, Codex, Cursor
• CI/CD: GitHub Actions, GKE

Work Responsibilities

• Periodically join your fellow product engineers in designing, implementing, and maintain high-quality Android features to understand their reality and define the best solutions for them.
• Own end-to-end development for platform and architectural solutions, from requirements definition through architecture, implementation, testing, and release.
• Lead architectural design for complex features and system components, ensuring maintainability, scalability, and reliability.
• Optimize app performance, startup time, memory usage, and stability across diverse devices and OS versions.
• Work closely with machine learning, backend, infrastructure, product, and design teams to deliver seamless mobile experiences, as well as other feature-owner Android engineering teams.
• Take ownership and evolve Mercari's mobile platform, SDKs, and shared modules used across teams.
• Drive high code quality through code reviews, automated testing, CI/CD improvements, and rigorous documentation.
• Champion engineering best practices and contribute to guidelines and standards across Client Engineering.
• Stay current with the latest developments in Android, Kotlin, Android Views, Jetpack Compose, coroutines, and mobile architecture patterns.
• Bring innovative ideas to improve user experience, developer experience, and operational efficiency.
• Take ownership of initiatives that span multiple teams, driving alignment and technical decision-making.
• Mentor junior and mid-level engineers, helping strengthen the overall technical capabilities of the team and the engineering organization.

Unique Challenges

• Enabling dozens of mobile engineers in delivering awesome experiences to our 20M+ users by leveraging a diverse skillset to provide the best mobile ecosystem.
• Deliver highly performant and reliable functionality in a fast-paced environment with complex product requirements.
• Bridge consumer-grade UX expectations with robust engineering architecture and infrastructure.
• Influence platform-wide technical strategy, shaping the future direction of Mercari's mobile and AI-native cross-platform ecosystem.
• Lead cross-functional efforts in ambiguous problem spaces where user needs and technical constraints must be balanced.

Qualifications

Required Experience/Skills

• Shared belief in the mission and values of the Mercari Group.
• Bachelor's degree in Computer Science, Engineering, or equivalent practical experience.
• Strong proficiency in Kotlin and Android development frameworks (Jetpack libraries, Jetpack Compose, Android SDK).
• Solid understanding of mobile architecture patterns (MVC, MVVM, MVI, Clean Architecture, etc.).
• Demonstrated experience with large-scale mobile applications and complex codebases.
• Experience integrating with backend APIs and asynchronous/concurrent programming.
• Strong analytical and problem-solving skills; ability to navigate ambiguity.
• Excellent communication skills and ability to explain technical concepts clearly.
• Passion for building user-facing mobile products.

Preferred Experience/Skills

• Experience with large-scale mobile apps serving millions of users.
• Expertise in performance optimization, instrumentation, and mobile observability (e.g., crash analysis, metrics).
• Experience with modern Android platform capabilities (e.g., Kotlin Multiplatform, Baseline Profiles, app performance tooling).
• Contributions to open-source Android projects or active involvement in the mobile community.
• Experience driving technical initiatives across multiple teams or owning platform-level components.
• Familiarity with CI/CD for mobile, automated testing frameworks, build systems (Gradle), and release management.
• UI/UX sensitivity and an eye for detail in crafting polished user experiences.

Language

• Japanese: Independent (CEFR - B2) Optional
• English: Independent (CEFR - B2) Required