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Developing His Ideas - The Everyday Life of an App Engineer at PayPay



PayPay provides all of its services to users through its smartphone app. It is no exaggeration that the app itself is the “face”, or, the “entirety” of PayPay.

This time, we sat down with Yoshimitsu Sakui, an app developer who works on the development of the app that contains everything PayPay has to offer.

【Professionals at PayPay】 is a series showcasing talented professionals who support PayPay.
Vol.5 Product Division Yoshimitsu Sakui He joined PayPay in January, 2019. He serves as a Tech Lead (Manager) in the PayPay app development team.

Making Improvements to the App without Relying on the Weekly App Update Cycle

– What kind of team is the Consumer App team, where you are the Tech Lead?

The app development team is divided into three sub-teams: the “SDK team” which builds development kits to enable connections with external services, the “Platform team” which develops and improves the core elements of the app, and our “Consumer App team”. Out of the PayPay app which is used by the consumers (i.e. users), we are responsible for delivering more convenience in the areas on which our users tap. There are both iOS engineers and Android engineers in the team, and we are in charge of developing new features as well as version upgrades of the app.

Specifically, we work on tasks such as responding to requests for improvements that are raised by users and other teams in the company, solving issues that arise in the app, and developing new features. However, developing the app is not something that can be done just by our team. We work with product managers (PMs), back-end engineers, designers, and web engineers for all feature developments.

Being a team that is fully responsible for developing the PayPay app, there are a lot of things to do, but I always engage in my development tasks thinking “I’m going to deliver a convenient cashless experience to our users through this app!”

– What do you value the most as the head of the Consumer App team?

Understanding what exactly the PMs, the leaders of the projects, want to create and what kind of UI/UX the designers want to achieve is something vital to us. We also want to share ideas within the team and create better services. So naturally, the amount of communication increases.

MTG of Consumer app team where Yoshimitsu is the tech lead (manager).  Yoshimitsu is the second from the left in the top row

And not to forget speed. Up until now, we have updated our app almost on a weekly basis to release new features and improve the usability. Since the launch of our service, the iOS app has been updated 125 times and the Android app 147 times. I don’t think there are many apps that have been updated this much.

– Why is the app being updated so much?

As we try to deliver a more useful app to our users, we find more and more areas that we want to improve, so naturally the number of updates increases. There is no end to the list of ideas for new features that we want our users to use.

However, what is unique about PayPay is that we do not limit ourselves to the weekly updates, but we improve features on an on-going basis.

What this means is that the weekly updates are not enough to keep up with our speed in delivering new features and improvements that we want to release. Sometimes we receive sudden requests such as “I want this changed by the end of today,” but responding to that saying “The next app update will be done next week, so please wait” is not good enough. Having said that, releasing an update requires the app to be screened after being developed, and some users don’t update their app in the first place, so we cannot increase the frequency any more than this.

Therefore, we have developed a mechanism to improve the app more frequently without having to depend on the app update. For example, we replaced the screens and modules that we used to build within the app with a website, and made it possible to change various content and fields such as texts and deep links directly from the back-end. I am confident that PayPay’s growth has been accelerated by being able to improve the app flexibly without relying on the app updates.

Whether or Not Our Service Will Be Used Depends on Our Development

– PayPay has a culture that values “outstanding speed” in any job. Please tell me the reason why speed is important in app developments.

We want to be the leader in the cashless payment industry and replace our biggest rival, cash. To do this, we need to add new features quickly and keep users using them. Also, when you think about it from the user’s point of view, if the app is going to be even a slight more useful than now, we should make improvements right away, and if it helps the app in becoming more useful, we should continue to add on more features. Of course, the major premise is to release it safely though.

Moreover, if you think of wanting to meet the expectations of the people in the company, you will naturally become conscious of speed. Not only among engineers, but we feel the enthusiasm for delivering services and campaigns to the users quickly as possible by people from every department.

However, even if a campaign or a service is created, it cannot be delivered to the users if we cannot display it on the app. So that motivates us, the team in charge of developing the app, to return the ball that everyone has worked hard on preparing, to users as quickly as possible. This requires some hard work at times.

– You have a strong sense of responsibility.

It needs to be done – that’s how I strongly feel. PayPay has 33 million users, and all of our services are delivered to these users through the app. Whether or not these many users will continue to use PayPay depends on how useful the app is. That means, it’s all up to us developing the app. Which reminds me how enormous my responsibility is, but at the same time it is also rewarding.

– What else do you find rewarding?

The company’s vision of “Making PayPay a Replacement of Cash” is a big challenge in itself, and is something that can be experienced only in PayPay. Japan has always had a cash-based culture, but we are trying to change this. Taking up a challenge like this is definitely not easy at all. It’s a difficult challenge, but I am deeply motivated to be a part of.

But I also feel anxious every day. The goals and policies laid ahead of us change very quickly, hence what is required in developing the app also changes rapidly. To be honest, I sometimes get lost not knowing what is right, and at times I continue pushing forward although while feeing anxious. I call this “a matter of survival” and sometimes I even feel like running away (laughs). I don’t know the correct answer, but we work on our development tasks every day while consulting with PMs, designers, and other departments such as the customer support team to find the best way.

Yoshimitsu interviewed online

An Environment That Allows You to Take on Challenges

– I heard that you were initially seconded from Yahoo! JAPAN and later transferred your employment to PayPay.

When PayPay was launched in October 2018, I remember looking at the “10 Billion Yen Giveaway Campaign” and thinking “That’s a lot of money being spent!” (laughs). After that, I was asked if I would want to be seconded to PayPay, and since I was attracted by the globalized development environment as well as the fact that I can take on the challenge of creating new services in a speedily manner, I ultimately decided to take the offer to transfer my employment completely to PayPay.

-It’s been about 2 years since you’ve joined PayPay. As an app developer, what do you think makes PayPay attractive?

The engineers are given considerable discretion. We’re not asked to only build things according to specifications, or to just be engaged in development work. We have an environment where it is easy to speak up our opinions like “I want to build something like this” or “I want the specifications to be like this”. Ideas from engineers are often accepted and this allows us to take on more and more challenges. I think this is something unique to PayPay. We have a common mindset that we shouldn’t be afraid of failure, and that if we fail, we learn from them and move on. I feel that we have an environment which also allows us to challenge what we want to do as individuals. Of course, if you propose an idea, you are expected to also produce results. So it comes with responsibility.

For example, when the release of iOS14 was decided, the app team came up with the idea of developing a “widget feature”. Being a completely new feature, we knew it would take time and effort to build it, but I was convinced that this feature can improve usability of our app, so I pushed for this idea to the executives and kick started the project. I had discussions with my team members every day on what the feature should be and went through continuous trial and error while gathering ideas along the way. After going through this experience, I was happy to see many positive comments such as “This is beyond convenient!” on SNS after we launched this feature.

– The app development team is currently active in recruiting members. What would you like to say to those who are considering of applying for the job?

I think that PayPay is unique in the sense that you are able to actively take on new challenges and that the impact of what you develop is enormous as it will reach 33 million users. Employees at PayPay are gathered from around 35 countries so if you are seeking to work in a development environment with global standards, and if you want to enrich society by promoting cashless payments, PayPay is indeed the place for you. Let’s work together to achieve our vision of “Making PayPay a Replacement of Cash”!

Click here for recruitment information of the Consumer App team for which Yoshimitsu is a Tech Lead (Manager).

iOS Engineer

Android Engineer
edited by daiki(PayPay Inside-Out Editorial Team) * Employees​’ affiliations are as of the time of the interview.