Large-Scale, Groundbreaking Split Payments Project that Changed PayPay’s System

This Project Story series focuses on what takes place behind the scenes of PayPay Group’s significant projects. We will delve into the difficulties and the pivotal mindset which led to the success of each project through anecdotes of members who were in charge.
In this issue, we interviewed the development members of Split Payments.

A Year-Long Project that Fundamentally Overhauled the Existing System

Tell us about your current responsibilities

Konno：
As a Senior Manager of the Platform & Core Components Division, which handles the crux of our payment system, I take care of management tasks such as creating teams and environments conducive to development.

Sunna：
As a Product Manager, I am in charge of defining feature specifications and managing both stakeholders and timelines.

Leo：
As a backend engineer and sub-leader of the Payment Team, I am responsible for designing and implementing new features, as well as maintaining the codebase to ensure the reliability and stability of our payment service.

What exactly are split payments? Please give us an overview of the project

Sunna：
It’s a feature that allows you to combine multiple payment methods in a single transaction. Increasing the options for payment methods is a significant benefit for users. For example, even if you had a remaining balance of 10 yen in a PayPay Gift Voucher, with the vouchers until now, you had to purchase a 10 yen item to use up the balance. That has been a challenge ever since the vouchers were under development. Moreover, the effective use and promotion of PayPay Points has been a significant topic for the entire PayPay Group in building our group’s economic zone.

Related link："Split Payments Possible When Paying with PayPay!"(Press release issued November 15, 2023)

The Day 1 release in early December involved two types of split payments: a combination of PayPay Balance and PayPay Gift Vouchers, as well as Credit with PayPay Points. We plan to support other combinations from Day 2 onwards.

Konno：
Although we’d been considering it since the first or second year of PayPay’s launch, we prioritized other features due to the hefty development load. With the release of PayPay Gift Voucher, the need for split payments grew significantly, leading to this year-long project.

Leo：
On the technical side, the previous system was built on the premise that a single transaction would be completed with one of the available payment methods, like Balance, Credit, PayPay Gift Voucher, and so on. Plus, PayPay Points were treated by the system as part of PayPay Balance.
On the other hand, split payments must allow for multiple payment methods in one transaction, with PayPay Points separated from Balance, which required a fundamental redesign of the architecture.

Looking back, how do you feel about the project?

Sunna：
The scope of Day 1 was to roll out the two types of split payments mentioned above, but it was still a large project involving almost all the tech teams. We had to find a way to control this large group and ensure that the project moved forward.

Therefore, we drew an overall schedule for releasing the product in three parts. In the first part, we established points as an independent payment method, which required adding it as a payment method on PayPay services used by the merchants as well. In the second part, we changed the format of the daily recon file, which is the transaction statement provided to merchants, and in the third part, we released two types of split payments.
Since it would significantly impact our merchants, we needed to plan things carefully, including six months’ notice in advance and providing both the new and old transaction statement formats for three months.

Konno：
We internally called the project “Complex Payments,” so the members were talking about the project being “too complex” (laughs). Handling edge cases due to having multiple payment methods was hard too. For example, what if one payment method fails? What if there’s not enough balance? We had to solve such issues one by one.

What was the hardest part of the project?

Sunna：
The project affected many areas internally, with many related sub-projects. This meant a lot of coordinating was necessary. As mentioned, we split things into stages and I divided tasks among Technical Program Managers, and even my manager, as it was too much to handle all by myself. We frequently held sync sessions within the team, sometimes oversharing to align our perspectives.

Leo：
The impact extended beyond the payment system, so we had to start by learning the system specifications of other services. Understanding what each team needed to do for this project and quickly integrating that into a comprehensive architectural design was very challenging.
I constantly communicated with other backend teams, focusing on maintaining an open and honest communication. Consulting senior members on difficult problems and seeking their cooperation was a major factor in a successful delivery. Collaboration both within and across teams was definitely crucial.

Please tell us about the future of this project

Sunna：
Efforts to fundamentally revise the core parts are not easily noticeable on the surface, and the response on social media after the launch was not significant. But I think people will notice that they have more options when making payments, and feel the app to be a bit more convenient than before.
This project is a quiet but significant step forward in improving the user experience and formulating the Group’s economic sphere.

Going forward, we aim to make improvements based on the following:

• Usage trends of PayPay Gift Voucher & PayPay Balance or Credit & PayPay Points payments
• Whether users feel any inconveniences with the UI/UX, and
• Differences in the use of PayPay Points across different payment methods.

In Day 2, we plan to introduce partial usage of points and other combinations, and continue with other initiatives down the line.

Responsibility and Satisfaction of Handling the Core System

What do you value in your work?

Konno：
As a Senior Manager, I value creating an environment that draws out each member’s potential to the fullest. PayPay is home to talented members from around the world with diverse backgrounds. I’m always thinking about how to collaborate and create an environment in which we can create even better things.
Another thing is, being responsible for the core part of the payment system, I make it a point of asking whether the task at hand is indeed a problem that needs solving and whether the chosen approach can actually solve the issue. Because we look after the core part of the payment system, I can’t just say, “Let’s give it a try and see how it goes.” We need to be a team that thinks things through, and only after that, try things out with the confidence that they will work. That’s how each step we take should be.

Sunna：
As a Product Manager, I always make sure that I am not the blocker. I take great care to avoid any oversight in Slack so that the project doesn’t stall waiting for my response. I tell my team members to make me take action if they don’t get a response within 24 hours.
I’m always thinking about how we can communicate better, for example, encouraging members to talk amongst themselves without me sitting in the middle.

Leo：
As the payment service is at the center of PayPay’s services, I always make sure I pay extra attention to each detail of the design and development. As the various product features become increasingly complex, it’s necessary to keep up-to-date with the latest specifications and design things in the most robust way possible. Currently, as a sub-lead of the Payment Team, it’s also important to me how I can enhance team motivation and achieve our sprint goals.

What is the most rewarding aspect about working at PayPay?

Konno：
The opportunity to solve various high-difficulty challenges with talented members from diverse backgrounds is rewarding.

Sunna：
Being involved in projects that have a significant impact on users is highly motivating.

Leo：
Realizing that my work affects people’s lives brings a sense of accomplishment. Seeing the PayPay logo at checkout counters or hearing “Can I use PayPay?” makes me happy. Also, refactoring the complex codebase to simplify vast codes into a few lines is quite the fun.

What would you like to accomplish or try in the future?

Konno：
There are still many challenges both organizationally and technically, so I want to create an environment where each member and team can tackle the challenges that should be addressed. Personally, I will continue to work hard to make the best decisions from both business and product perspectives.

Sunna：
I would like to take on another large project like this one. I hope to use the feedback we received this time to improve our processes and make them smoother.

Leo：
I also want to take on an even more challenging project! Additionally, I will work on improving the overall performance and stability of the payment system and aim to achieve zero downtime.

Lastly, a message for our readers please!

Sunna：
If you are proactive, curious, and passionate, you will thrive at PayPay.

Leo：
We welcome those who are eager to grow without compromising, and value cooperation with others.

Konno：
Anyone committed to learning is welcome. Let’s enjoy the challenges and personal growth together!

*Job openings and employee affiliations are current as of the time of the interview.