About Company
Mercari is Japan’s largest C2C marketplace, revolutionizing the way people buy and sell second-hand items. Our mission is to ‘create value in a global marketplace where anyone can buy & sell, and connect with each other.’ Since our founding in 2013, we’ve grown rapidly, expanding our services beyond the core marketplace to include payment solutions (Merpay) and other ventures. We are a diverse and dynamic team, embracing a culture of bold challenges and innovation, constantly striving to build a more sustainable future by circulating resources. Joining Mercari means becoming part of a passionate group dedicated to delivering seamless and delightful experiences to millions of users daily.
Job Description
Are you a budding React enthusiast eager to kickstart your career in a fast-paced, innovative environment? Mercari is looking for a passionate and driven Junior React Developer to join our growing engineering team in Tokyo. This is an incredible opportunity for someone with foundational knowledge of React and a strong desire to learn and contribute to a product used by millions. You’ll work alongside experienced engineers, receiving mentorship and guidance as you develop your skills and take on meaningful challenges. We believe in empowering our engineers, even at the junior level, to make an impact. You’ll be instrumental in developing and maintaining user-facing features for our flagship Mercari marketplace application, focusing on creating responsive, performant, and delightful user experiences. If you’re ready to dive into a modern tech stack, collaborate with a diverse and talented team, and see your code deployed to production quickly, this role is for you. We value curiosity, a proactive attitude, and a commitment to continuous improvement. Come grow with us and help shape the future of commerce!
Key Responsibilities
- Develop, test, and maintain user-facing features using React.js and modern web technologies.
- Collaborate closely with senior engineers, product managers, and designers to translate requirements into technical solutions.
- Write clean, well-documented, and performant code, adhering to established coding standards and best practices.
- Participate in code reviews, providing constructive feedback and receiving insights to improve your skills.
- Assist in identifying and resolving frontend bugs, performance issues, and UI/UX challenges.
- Contribute to the continuous improvement of our development processes, tools, and infrastructure.
- Actively learn new technologies and industry trends to enhance personal and team capabilities.
Required Skills
- Proficiency in JavaScript (ES6+) and its core principles
- Solid understanding of React.js and its ecosystem (hooks, context API, etc.)
- Familiarity with modern HTML5 and CSS3 (including preprocessors like Sass/Less or styled-components)
- Experience with version control systems, particularly Git
- Basic understanding of RESTful APIs and asynchronous request handling
- Strong problem-solving skills and a proactive attitude towards learning
- Excellent communication and teamwork abilities
Preferred Qualifications
- Experience with TypeScript
- Familiarity with state management libraries like Redux or Zustand
- Knowledge of testing frameworks (e.g., Jest, React Testing Library)
- Understanding of build tools such such as Webpack or Vite
- Experience with GraphQL
- Basic understanding of CI/CD pipelines
- Business-level Japanese language skills (JLPT N2 or higher) or a strong willingness to learn
Perks & Benefits
- Comprehensive social insurance (health, pension, employment)
- Visa sponsorship and relocation support (if applicable)
- Flexible work hours and remote work options within Japan (team-dependent, on-site for this role)
- Generous paid time off and special leave policies
- Employee stock options program
- Commuter allowance
- Free lunch and dinner on-site, plus a variety of snacks and drinks
- Regular social events and team building activities
- Access to a comprehensive learning and development budget (conferences, courses, books)
- Modern, open-plan office in a prime Tokyo location
- English-speaking environment and language learning support
How to Apply
Ready to launch your career with Mercari? Please submit your resume, cover letter, and any relevant portfolio links (e.g., GitHub, personal projects) through our official careers portal. We encourage you to highlight your passion for React and any projects you’ve worked on, no matter how small. Our recruitment team will review your application and reach out if your profile aligns with our needs. We look forward to hearing from you!