Tech Talks vol.25 – Backend Tech Lead

About Tech Talks

In this Tech Talks series, we will share with you the attitude and vibe of the PayPay Tech Team through the voices of the unique product members from around 50 countries!
In this installment, we spoke with Yusuke, Tech Lead of the Merchant Team.

Tell us about your job and your mission

The Merchant Team develops and maintains the backend for merchant management services. We manage the master data for all merchants including transaction and fee settings and location data and are responsible for things like using APIs to provide data during transaction processing.

One of our missions is maximizing speed. Users don’t want to wait second upon second for their transaction to finish after showing their two-dimensional code, so every hundredth of a second we can shorten transaction processing counts in improving the UX. We do the same when providing merchant information, using techniques such as caching to speed up response times as much as possible.
Our other mission is to ensure accuracy. We are especially careful in design and development related to fee-related data since fee calculations systems are highly complex and any mistakes would inconvenience merchants.

As the Tech Lead of the Merchant Team with technical responsibility for the projects my team develops, I hear out, design, and check project requirements. Some projects require detailed checks early on, while others only need a quick look at the end, so we adapt how we work based on the difficulty of each project and the team members responsible for it.

What made you decide to come to PayPay?

I worked at my first company out of university for about four years, the last few of which were spent in the Singapore office developing tools to help in-house engineers create databases. The reason I changed jobs was that I wanted to develop products that have a social impact. I wanted to get involved in the development of products that my friends, family, and everyone else uses. Being in Singapore at the time, I only knew PayPay by name, but I decided to join because I felt that it was an environment where I could fulfill this desire. I also wanted to work with more experienced engineers and felt that PayPay clicked with my goal of growing as an engineer in an uncompromising environment.

I joined the company in the fall of 2019, when we were about to add and release many new features to our app, so it was the perfect environment for me to take on lots of tasks and take my engineering to the next level. Since joining, I’ve been part of two teams and also experienced being a Tech Lead and feel there is a clear-cut difference in my ability now compared to when I started here.

What challenges have you faced at PayPay?

The way we calculate merchant fees change several times a year, and I always find it challenging putting together a new system while ensuring accuracy.
In order to faithfully reflect business-side rule changes on our system, we change how it maintains data, but it’s quite difficult to incorporate new settings without impacting existing ones.
To accomplish this, it is important to understand exactly what the rules are, both old and new. A shallow understanding of the rules will eventually become obvious on the system. We clarify the fine details of changes through talking about the background behind them with the responsible members on the business team, and I’m careful to ensure that these conversations deepen not only my understanding, but the understanding of my entire team. I make sure the necessary information gets to all developers by sharing it or having them attend meetings together with me.

What is the allure of working as an engineer at PayPay?

One great part is being able to take on as many new technologies as you could possibly want. Some Japanese companies use old technologies or versions of Java that haven’t been updated in years, but at PayPay, we are encouraged to constantly upgrade to newer versions, and we are even able to incorporate new frameworks.
Our backend uses a microservices architecture with more than 100 microservices each with their own independent structure, meaning that individual teams can adopt new technologies.
We are even working on a plan to completely overhaul the tech stack of the service I currently oversee for registering new merchants.

I also like the fact that we are able to allocate resources for engineer-initiated projects. Anyone with an idea for an improvement is allowed to make a proposal, and we can allocate the time needed to work on that improvement. I feel that PayPay is an engineer-first company.

And the biggest allure of working here is the constant sense that the products I am making are being used by many people. There aren’t many companies you could work at whose products are used by almost all your friends and family.

How is your team’s vibe?

I think we have a lot of highly ambitious engineers. Especially recently, more members have joined our team who all bring in a lot of enthusiasm that constantly adds to our team’s fire.
Many of our engineers also work hard to understand the details of requirements and the background that led to the change or implementation at hand. That’s one point I focus on when conducting interviews ― personally, I think a deep understanding of a system’s business requirements is more important than technical aspects like being able to implement algorithms efficiently.

How have you grown since joining PayPay?

Since becoming a Tech Lead, I have learned through the growing number of opportunities I have to check my members’ results that it’s important not to impose my way of doing things as the “right” way. I used to expect my team members to do things the same way I did, but this sometimes led to their discontent. I now know that there are many ways to reach the same goal and have come to respect the approach of each team member.
I think this growth was made possible because of our global workplace environment, with members from different countries and cultures. Everyone can employ their own ideas and processes to work toward the common goal of making PayPay a more stable, convenient service, making for a very stimulating work environment.

What do you want to try out next at PayPay?

I want to continue modifying data structures so that we can respond to new functional requirements as soon as we get them. I also have plenty of other ideas for improvement, which I hope to implement together with the whole team.
I also want to step up our team’s game by developing the skills of individual members so that they can complete projects without relying on the PM or Tech Lead.

Finally, do you have a message for potential candidates?

The number of PayPay users and merchants is soaring, and with new features being released every month, our environment has plenty of opportunities for growth. I myself chose PayPay in part because I wanted to work in an environment where I could grow, and since joining, I’ve gained experience through many projects and built up a distinct difference in skill from when I started. The word “Japanese company” may dredge up images of a company where decisions are made from the top down or where engineers’ opinions go unheard but rest assured that PayPay’s culture is not like that at all.
I believe that beyond technical skills, you will be successful here if you have a growth-centered mindset!

*The recruitment status is current at the time of the interview.

Special Thanks: Yusuke Kurokawa / Editor: Moe / Author: PayPay Inside-Out Editorial Team / Photographer: Tak
*Employees’ affiliations are as of the time of the interview.