Senior Software Engineer - Frontend

About Mercari

Mercari is a Japan-based C2C marketplace company founded in 2013 with the mission to “Create value in a global marketplace where anyone can buy & sell.” From being the first tech unicorn from Japan before its IPO in 2018 we have come a long way towards becoming a global player and continuously and diligently work towards our transformation journey with a strong focus on our mission. 

Since its inception, Mercari Group has worked to grow its services, investing in both our people and technology. Over time, Mercari has expanded from being the top player in the C2C marketplace in Japan to new geographies like the U.S. We have also successfully launched new businesses such as Merpay, which is a mobile payment service platform with a vision to create a society where anyone can realise their dreams through a new ecosystem centered not only on payment service but also on credit. Today, Mercari Group is made up of multiple subsidiary businesses, including logistics, B2C platform, blockchain, and sports team management.

About Mercari India 

Established in Bangalore in 2022, Mercari India serves as a crucial technology hub for the Mercari Group. Leveraging the rich and diverse tech talent in India, we primarily collaborate closely with our development hub in Japan to drive engineering development for Mercari's applications. Having grown to an organization of approximately 100+ members over about three years since its inception, Mercari India aims to evolve into an even stronger engineering organization that spearheads technological innovation for the entire group. This will be achieved by further enhancing our engineering capabilities and promoting AI initiatives that reflect India's cutting-edge technology and knowledge.

Our Culture

To achieve our mission at Mercari, our organisation and each of our employees share the same values and perspectives.

Our individual guidelines for action are defined by our four values:

• Go Bold
• All for One
• Be a Pro
• Move Fast

Our organisation is also shaped by our four foundations:

• Sustainability
• Diversity & Inclusion
• Trust & Openness
• Well-being for Performance

Regardless of how big Mercari gets, the culture will remain essential to achieving our mission and something we want to preserve throughout our organisation. 

We invite you to read the Mercari culture doc that summarizes the behaviours and mindset shared by Mercari and its employees. We continue to build an environment where all of our members of diverse backgrounds are accepted and recognised, and where they can thrive while holding dear to Mercari’s culture.

About Role

We are looking for a frontend engineer to own Mercari's web experience end to end. At Mercari, engineers work as Product Development Engineers (PdEs): you hold a deep specialization in frontend, and you use it to define what to build, prototype early, and stay accountable through release and production. Beyond your own delivery, you are the frontend enabler for cross-platform engineers - Backend, iOS, Android, and QA - joining technical discussions and planning early so they can work AI-natively in web code instead of waiting on you. This is a hands-on role on a large-scale product where rendering strategy, Core Web Vitals, and SEO directly shape the buying and selling experience.

Job Responsibilities

• Own frontend delivery end to end: problem definition, AI-assisted prototyping, implementation, release, and production ownership — observability, rollback, and follow-through on incidents.
• Build and evolve large-scale web applications with React and Next.js, owning rendering strategy, Core Web Vitals, and SEO for the buying and selling experience.
• Act as the frontend specialist and enabler for cross-platform engineers (backend, iOS, Android, QA): review their web changes, pair with them, and set the patterns, guardrails, and AI skills that let them ship safely.
• Join technical discussions and planning as the frontend voice — scope, architecture, sequencing, trade-offs — and turn incomplete specs into working prototypes so decisions don't stall.

Skills Needed

• Frontend: HTML5, CSS3, JavaScript (ES6+), TypeScript, React, Next.js, RSCs, SWR, Jotai (or similar state management library like Redux, Context API, etc.)
• Testing: Playwright, Jest, Vitest, Storybook
• APIs: ConnectRPC, protobuf
• Development tooling: pnpm, Turborepo
• Infrastructure: Google Cloud Platform
• AI-Assisted Development: AI coding assistants, skills
• Other Tools: GitHub, GitHub Actions, Slack, Jira, Octopus Deploy, Datadog, Sentry

Minimum Requirements

• Alignment with Mercari Group's mission and values.
• 5+ years of frontend experience with JavaScript, TypeScript, React, and Next.js, including hands-on App Router and SSR.
• Experience developing and operating large-scale products.
• Performance and scalability focus, including Core Web Vitals.
• Solid HTML and CSS skills, with expertise in ensuring cross-browser compatibility.
• Proficiency with Git, including within a monorepo structure.
• Effective use of AI coding assistants: skills and project instructions, efficient token usage, matching model and effort to task criticality, and thorough review of all AI-generated code.
• Willingness to work beyond the frontend boundary when the product needs it, with frontend depth as the foundation.
• Strong communication skills.

Preferred skills

• Experience moving CSR pages to SSR while preserving SEO and performance.
• Ability to evaluate and introduce new libraries and frameworks.
• Architecture design and/or TDD based on application characteristics.
• Proactive approach to continuous application improvement.
• Experience with SEO, structured data, and internationalization (i18n).
• Hands-on work with design systems and automated testing.
• Experience creating AI skills and agent workflows.
• Knowledge of accessibility standards (WCAG).
• Cloud platform experience (GCP preferred, or AWS).
• Familiarity with CI/CD and release processes.
• Open-source contributions.

• Employment Status: Full-time
• Office Location: Bengaluru, India
• Hybrid Workstyle: 2 days work from office / 3 days work from home per week.

We believe in high performance and professionalism. To build a strong and highly engaged organization in India, we encourage everyone to work from our Bengaluru office, especially during the setup phase. We continuously review and update our policies to align with future organizational needs.

Media & Resources

Owned Media

• Mercari Engineering Portal
• Mercan - Introduces the people that make Mercari
• Mercari US Blog

Related Articles

• https://engineering.mercari.com/en/blog/entry/20210810-the-new-mercari-web/
• https://engineering.mercari.com/en/blog/entry/2020-04-15-112744/
• https://engineering.mercari.com/en/blog/entry/20210630-connecting-the-dots-web-accessibility-through-internationalization-and-localization/

https://mercan.mercari.com/articles/29662/