Mercari launched as a service in 2013 and managed to amass more than 20 million monthly active users in just eight years. But right now, a large-scale revamp of our development platforms is happening behind the scenes to support our front-facing growth.

We call this project Robust Foundation for Speed (RFS for short). It is meant to support disruptive growth across all of Mercari Group, by solving complex technical challenges and drastically strengthening the foundation shared across our businesses.

In this Mercan series, we interviewed four key people leading this very large-scale project. We walked through each of their careers as we took a look at their involvement in this project and why this project is happening now. Following our interviews with Mercari CTO Ken Wakasa, RFS Project Owner Minoru Tsuka, and Transaction area Engineering Manager (EM) Hidenori Goto, we spent time speaking with Backend EM Mohan Bhatkar (@mohan).

Studying coding on his own as a university student put him on the path to working as an engineer at a Japanese company

ーTo start things off, could you tell me some of the backstory about how you became an engineer?

Sure. Originally, I majored in electrical engineering at university. Although I was studying engineering, I was a world removed from software, since I was studying things like designing and developing the microprocessors for smartphones, computers, tablets, and other such devices.

However, even as a first-year student, I also had an interest in programming and coding, and I kind of liked it. That’s why I gave coding a try on my own while I was still at university and started studying it alongside electrical engineering. That experience is part of the reason why I found a job as an engineer at Rakuten after graduation.

ーAnd that’s what brought you from India to Japan.

Right. At that time I couldn’t speak Japanese at all, so before I immigrated here, I did some Japanese language training courses and proficiency tests. Once I was in Japan, I took some training courses to learn programming and software development, and then after that I joined my team at Rakuten.

ーThe system your former company had in place for welcoming new employees seems to have taken care of everything. Once you were here, was there anything about living in Japan that you found hard?

At first I was on a team in charge of Rakuten Travel. But even though I received training, my experience with web development and my knowledge of computer science weren’t perfect. These ended up being daily challenges for me.

In addition, the service that I was in charge of catered to the Japanese market, so both the frontend and the backend of the website I worked on were both written in Japanese. For me to understand all of that properly, I had to work hard on my Japanese language studies, which was tough. However, when you have a job, you end up having to internalize something new pretty much every day. On top of that, no one expects you to do every single work task by yourself. Partly because I believed this, I learned Japanese at work by speaking it with other Indians on my team, who had joined the company before me, as well as with members from other countries. When I think back on it, that experience is what taught me to speak Japanese (laughs).

Mohan Bhatkar（@mohan）

ーWhat kind of experiences did you have after that?

I worked as an engineer for about four or five years. During that time, I was put in charge of the transaction system, the innermost core of Rakuten Travel’s infrastructure. Right around the time I joined the company in 2011, Rakuten was switching their service from an old system to a newer one. Working on that was a great experience for me.

ーWhat made Rakuten switch their system?

Rakuten Travel was already a giant of Japan’s domestic travel market, but for the company to extend their reach even further, they needed to use the Rakuten API.

ーThat’s a lot like what Mercari is now trying to do with our Robust Foundation for Speed (RFS) project.

You could say that. One small difference is that Rakuten’s system, which was created in 2005, was changed in 2011 into one that had an API-first approach, effectively modifying the service to be built around the design of the API. On the other hand, the system that Mercari built in 2013 was created with an API-first approach from its inception. The system that my team is in charge of—the CS Tool team—came to be in sort of a similar fashion.

That’s why my first impression of Mercari was that it wasn’t really that much of a monolith system. However, as business has grown quickly over the past eight years, the API has also become massive, and it cannot be expanded any further. This is the reason why we are going to be working on RFS going forward.

Even for the system at my previous workplace, sometime around 2016 to 2017, the company went through a phase where they split and cut what had become a massive API. In the software business, there’s a cycle of about five to six years that ends with the API becoming fat with features and needing to be split and rewritten.

Why he focuses on his role as a manager

ーWhat led you to join Mercari?

In my work I learned a lot about the large-scale services that juggernaut Rakuten offered. While I was with them, I gained technical expertise and management experience, so next I wanted to test my skills in a different environment. I had always been interested in what it would be like to work at Mercari, which began as a startup and then simply continued to grow, so I decided to sign on with the company.

ーI seem to recall you joined in 2019. What kind of work did you do when you joined?

When I joined Mercari, the company was in the middle of separating what were becoming a complex API and a complicated CS tool. Apparently, one of the reasons I was hired was because of my experience with system switching at my previous company. Once I was onboarded, my first task involved supporting the migration of microservices. And having entered the company as an EM, I also worked on managing the CS Tool team in my first year.

ーYou said that you were an engineer at your previous workplace. Did you find it at all confusing to be at Mercari in a mainly managerial role?

To be honest, I never really thought of myself as an incredibly talented engineer. And on top of that, I didn’t think I could succeed at any big challenges or missions alone. More than anything, I wanted to lead a team of various experts and work with them, rather than try to develop software on my own. In doing so, I wanted us to achieve our business goals and mission, and work to resolve issues. This is the reason why I changed roles from engineer to manager.

ーDid you see your new role in a positive light?

The difficulties and the challenges a person faces largely depend on the career path a person chooses, so people tend to choose a path based on what they are personally interested in. For me, having a sense of responsibility was crucial. So I sort of chose to go into management from that perspective as well. I think that anyone who shares this mindset will likely enjoy being in management.

Working at Mercari reminded him of the importance of reviewing his work

ーWhen you compare the image you had of Mercari before you joined with what you saw once you were a member, what were some of the differences?

When I joined Mercari, the company still had a lot of its growth phase ahead of it, so compared to my previous workplace, things like corporate governance and the organization of our divisions weren’t systematized enough, and I found that the company was also grappling with a lot of challenges. On the other hand, I entered the company already thinking about how to best go about tackling management work, so my impression of Mercari didn’t change all that much once I was on the inside.

Two years have passed since I joined Mercari. In that time, the challenges we’ve faced and how we’ve dealt with them have continued to change from one phase to the next. For me, it’s been a continuous learning process.

ーHave the differences between working at a major company versus working at a startup given you any new insights?

I feel that the best thing about Mercari is that we are very meticulous about reviewing what we’ve done. From our CEO and the heads of our engineering organizations to the members on each of our teams, if we take on a new challenge and it does not work out, we discuss where things went wrong and what was missing from the process. From there we find things that we can improve on, figure out together what we can do better next time, and then apply our ideas. That’s what I find appealing about Mercari.

For the past four or five years, our management, including people like @wakasa (Mercari CTO, Ken Wakasa), have been plotting the course that our engineering organizations should take with regard to things like RFS. The initiatives and review processes for such things are not taken lightly. The launch of this project is the result of that.

That’s not to say that these things did not happen at my previous workplace. However, at Mercari, I once again learned the importance of the review process. I feel like it’s tied to my own personal growth.

Our CS tool may be for internal use, but we did not accept any compromise on this indispensable element of business growth

ーCould you tell me how the area you are in charge of is involved with Mercari’s forward-looking focus on RFS?

The RFS initiative that we are working on now started with the acknowledgement that in order to expand our business going forward, we had to make changes to our software system, which has grown in complexity as Mercari has continued to develop and operate it over the past eight years.

The CS tool that I am now working on was also first created eight years ago. Currently, in addition to using the tool to handle user inquiries, we’ve been adding various features to it such as one for making lists of detailed information and listings and one for detecting listings that violate our rules.

To grow our business, it’s also crucial to create and operate a platform that can process CS operations and internal applications properly. That is the task of the CS Tool team. As an EM, when an issue emerges, I resolve it while speaking with the CTO or other members of the company leadership, and I try to get my team to advance their projects as smoothly as possible. That’s job number one for me.

ーFor your current project, did you decide to work on the CS tool because it was already nearing its breaking point? Or are you aiming to prepare for Mercari’s future business expansion?

When we considered the complexity of the current system, we saw that it had already reached the limits of its capacity. Over the past seven years, the number of users on Mercari has gone through the roof, so it makes sense that the number of operations that CS handles has increased. Our members have to handle inquiries carefully, and at the same time, they also need a system that can handle future expansion.

ーIncidentally, did you have a tool similar to Mercari’s CS tool at your previous workplace that optimized the handling of user inquiries?

Yes, there actually was a similar tool for internal use. Compared to the tool I used back then, I get the impression that Mercari’s CS tool isn’t just for handling customer inquiries, but rather has all of the features necessary to execute a variety of internal operations.

At the risk of being misunderstood, let me just say that a CS tool is designed for internal use, and so depending on the company, some people will think, “if it gets the job done, what more can I ask for?” Mercari’s culture says that even internal tools are important for growing our business.

ーWhat would you say is your biggest motivator for being involved in this RFS project?

One of the things that motivates me is having the chance to focus company-wide on a system that we have operated for eight years, and which has become more and more complex with time, with an awareness that we must change the foundation that supports our growth as a company. Even compared to other Japanese companies, I think the RFS project is a rarity. I also think that having the opportunity to rewrite a piece of software is in itself a valuable experience, and a chance to grow extensively as an engineer.

Another thing that motivates me is the rather substantial challenge of investing in our foundation and implementing RFS without interrupting Mercari’s business growth. Especially because Mercari deals with a lot of new businesses and challenges, creating a system that can also withstand substantial change and that has a CRE (customer reliability engineering) perspective is very challenging.

ーMercari is looking for people who can help us achieve the goals of this project. Is there anything you’d like to say to people who are thinking about applying to Mercari?

Yes, actually. Mercari’s API and CS tool are built using PHP. If you have development experience using PHP, or if you are motivated by working to develop a business and an engineering environment, I think the RFS project we are working on will be a good chance for you to grow.

This RFS project won’t end with the revamping of the CS tool. Once that’s done, we’ll use new technology to continue to handle the scale of the business as it grows. I definitely hope to hear from anyone who wants the opportunity to do their best work and from anyone who is even a little interested in what we’re doing.

In conclusion

We hope that this article helped you better understand one of the key people leading Robust Foundation for Speed. We are looking for members who can help us achieve the goals of this gigantic project.

If you’re interested, please click the link below to learn more. You will find more technology-focused Mercari Engineering articles written by various project members, as well as information about our hiring events.

We’re looking forward to meeting you! Click here to apply!