Robust Foundation for Speed

We aim for disruptive growth across all of Mercari Group. To support that, we’re working on a project to solve complex technical challenges and drastically strengthen the foundation shared across our businesses.

What is Robust Foundation for Speed?

Our engineering organization has been working to migrate the Mercari marketplace app to a microservice architecture since 2017. By doing so, we’re slowly but surely shifting the infrastructure that supports our services to a more modern platform. But it hasn’t exactly been the easiest of tasks. Migrating our transaction system, one of Mercari’s core features, has proven to be a challenge, and even now it’s still running on the PHP-based monolithic application we’ve been using since Mercari’s inception.

That needs to change. Maybe we can’t move it all to microservices right away. But in the meantime, we need to boost maintainability and scalability somehow, and that’s how we arrived at a new approach: a modular monolith, where we create modules within the monolith.

As an engineering organization, we want to be adaptable and flexible to support disruptive growth for the entire Mercari Group: not just Mercari, but Merpay, Mercoin, Souzoh (Mercari Shops), Merlogi, and whatever comes next. With this project, Robust Foundation for Speed, we aim to realize that goal by solving complex technical challenges and drastically strengthening the foundation shared across our businesses.


Event information

Mercari regularly hosts casual engineering events and study sessions.
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Position Overview

We need PHPers for this project! Whether you have experience in refactoring/maintaining large-scale PHP applications or want to put your skills to the test in taking on this tough project, we’d love to work with you.

This position allows full-time remote work from anywhere within Japan. You can choose whatever work environment lets you demonstrate your best performance and value—as long as you’re willing to commit to the project, where you do so is up to you.

Work Responsibilities
  • Developing and maintaining core features (PHP; Go, etc. as needed)
  • Designing loosely coupled/modular systems
  • Working with PMs on development tasks from start to finish (planning, design, implementation, QA, release, etc.)
  • Investigating inquiries from customer support or other development teams
  • Conducting system operation tasks, including responding to alerts while on call
Bold Challenges
  • In this position, besides your software engineering skills, you will be expected to utilize your comprehensive problem-solving skills. You will need to approach problems by setting and testing hypotheses, and you will need a lot of curiosity and attention to detail in order to tackle core systems that run a huge number of item transactions everyday.
  • These are important systems that handle user assets, so it’s important to go beyond the team’s domain to understand the features’ end-to-end behavior and how they relate to other features. Some features, however, can be hard to fully understand simply by reading the code because they are too complex or old.
  • This will require that you embrace some level of uncertainty and strategically set and test hypotheses. Additionally, you will need to always keep your goals in mind and try to find solutions by thinking outside the box.
Required Experience
  • Shared belief in Mercari’s mission and values
  • Experience developing and operating systems for large-scale products, selecting technologies, and improving their codebase
  • Experience in API development using programming languages such as Go, PHP, or Java
  • Experience designing and developing databases (MySQL or a similar RDBMS)
  • Ability to design and develop products while considering performance and scalability
  • Extensive knowledge of object-oriented software development, networks, memory management, and software testing
  • Good communication skills to collaborate with stakeholders and teammates on product development
Preferred Experience
  • Domain knowledge in e-commerce, order management, payments, shipping, delivery, etc.
  • Experience with project management or team leadership
  • Experience with Scrum
  • Experience developing and operating systems using microservice architecture
  • Knowledge of and experience with databases (RDBMS/NoSQL), networks, Linux, monitoring systems, logging, and SLO/SLA
  • Experience with software development in the cloud (GCP, AWS, and/or Azure)
  • Experience contributing to an open-source project
Language Requirements Fulfills either of the following:

  • English: Basic (CEFR – A2) preferred / Japanese: Proficient (CEFR – C1)
  • English: Proficient (CEFR – C1) / Japanese: Basic (CEFR – A2) preferred

※*For details about CEFR, seehere.

Employment Status Full-time

  • Probationary period: First 3 months after joining the company. (During this period your contract conditions will be the same as that of a permanent employee.)
Office Your choice

  • Mercari has introduced a work style policy called “Your Choice.” Each member is free to choose whether they want to work in the Roppongi office or fully remote from anywhere within Japan.
Work Hours Scheduled working hours: 10 AM – 7 PM

  • Currently, due to the COVID-19 pandemic, we have introduced a full-flex system without core time to increase the choice of working hours and allow for more flexible working styles.
  • Two days off per week (as well as national holidays, New Year’s break, etc.)
  • Paid leave, congratulatory and bereavement leave, relax days, sick leave
  • Paid monthly (including fixed overtime allowance)
  • Based on skills, experience, and abilities
  • Reviewed twice a year
  • Complete health and social insurance
  • Incentive program
  • Support systems, including those that benefit employee family members
  • Language learning support
  • Translation/interpretation support
  • *Seethis pagefor details.

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