This position is closed and is no longer accepting applications.

Software Engineer, Backend (ID Platform)

Mercari Minato-ku, Tokyo
  • 💴 No salary range given
  • 🏡 Fully remote (from Japan)
  • 🧪 5+ years experience required
  • 💬 No Japanese required
  • 🌏 Apply from abroad
  • 🧳 Relocate to Japan

About Mercari

Mercari Minato-ku, Tokyo

Mercari is a marketplace app that makes it easy for people to safely sell and ship their things. Having been downloaded over 100 million times, it is now among the largest peer-to-peer selling platforms globally.

Key benefits

  • Full flextime
  • Outside work encouraged
  • Employee stock ownership program

About the position

As a software engineer in the ID Platform team, you will support Mercari Group’s growth with not only skills in the backend domain, but also expertise in the authentication and authorization domain.


The ID Platform team is a dedicated team that provides the authentication and authorization platform for both marketplace and fintech businesses.


  • Handle authentication and authorization platform development
  • Providing authentication and authorization-related solutions to teams/projects across the whole Mercari group.
  • API/interface design for microservices using Protocol Buffers and gRPC
  • Improving services and measuring effectiveness using quantitative and qualitative analysis on user behavior logs, etc.
  • Design architecture and select middleware based on application requirements
  • Microservice performance tuning, monitoring, and alert handling
  • You will be able to work on a large-scale authentication and authorization platform that supports the huge customer base for both Mercari. The platform is both internally and externally critical. It will not only support the internal microservices but also be used by our partners for system integration purposes.
  • This platform is built on our own. You will tackle the complex security and user experience problems along with your expert team members.
  • You will dive into the deep ocean of OAuth 2, OpenID Connect, working with your team to renew the legacy authentication feature in a monolithic service by creating new microservices following the OpenID Connect standard.
  • During the process of designing and building the platform, you can gain a deep insight into related RFCs and Internet-Drafts.
  • You will work in a super diverse team with teammates from more than 8 countries and areas to support other teams who use both Japanese and English


  • Shared understanding and belief in Mercari Group mission and values
  • 5+ years of experience in web application development
  • 3+ years of experience in authentication and authorization development
  • Working knowledge of OAuth 2, and/or OpenID Connect
  • Enthusiasm for solving problems in the authentication and authorization domain
  • Experience designing schemas and creating effective queries for databases (such as RDB, NoSQL, etc.)
  • Experience operating web applications and conducting performance tuning, knowledge of security
  • Experience selecting middleware and designing software architecture
  • Ability to take ownership and lead the software development process

Nice to haves

These aren’t required, but be sure to mention them in your application if you have them.

  • Expertise knowledge in OAuth 2, OpenID Connect, WebAuthn/FIDO 2, and other well-known auth schemes.
  • Experience developing and operating using Go, PHP, GCP
  • Experience developing and operating large-scale, high traffic system
  • Experience establishing new services and tackling the challenges in the growth phase of a service
  • Experience as developer lead or management/experience improving the development process
  • Experience in statistical data analysis

Meet Mercari's Developers

Jieqiong shares her experience of joining Mercari and working as a tech lead. She explains their engineering culture and provides tips for potential applicants.

Read her story...

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