With over 75 million users (as of August 2026), PayPay has become one of Japan’s leading FinTech platforms. Together with PayPay Bank, PayPay Card, and PayPay Securities, we are building the next generation of digital financial services across our group companies.
At this event, lead engineers from each company will share the unique technical challenges of their respective growth phases. They will also show how we collaborate closely as a PayPay Group to build Japan’s No.1 digital financial platform.
PayPay Developers Meetup is designed for engineers eager to discuss complex technical challenges and curious to go behind the scenes of PayPay Group product development. It is a unique, in-person opportunity to experience our hands-on engineering environment and vibrant, international culture first-hand.
Come exchange ideas, connect with our team, and explore your future at PayPay Group!
PayPay Developers Meetup in Tokyo
Event Overview
Event title：PayPay Developers Meetup in Tokyo
Date：September 16, 2026 (Wed) 19:00-21:00 JST
Venue：PayPay Yotsuya Office (Comore Yotsuya 23F)
- Time
Content
- 19:00-19:10
Opening
- 19:10-20:30
Presentation from each group company
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Enabling Reliable Frontend Delivery at Scale/ Sutthikorn Saengrungruangsri（Frontend Engineer, PayPay Corporation）
In this session, we will share the Change Management Platform we are building at PayPay. Serving as a unified control plane that integrates fragmented frontend delivery pipelines, it provides teams with real-time visibility into release readiness, build accessibility, and production stability at scale.
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How PayPay Bank is modernizing its core banking system/ Shotaro Konno（Senior Engineering Manager, PayPay Bank Corporation）
In this session, we will introduce PayPay Bank’s project to modernize its core banking system using AI. We will share our approaches to modernization while preserving the business logic and reliability of the existing system, with a particular focus on AI-assisted development and Harness Testing, which verifies the new system by comparing its behavior with the existing one.
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A graph-based approach to modelling company knowledge/ Bob Merlet（Backend Engineer, PayPay Card Corporation）
Organizational knowledge lives across team chats, code repositories, wikis, cloud storage, and spreadsheets. The challenge isn’t creating documentation—it’s finding the right information, understanding its context, and maintaining proper access controls. While vector databases optimize text search, a graph database adds vital context by mapping connections across people, documents, conversations, systems, and topics. In this session, we will share how starting with an internal communication tool as a practical first use case allowed us to master graph technology, validate key assumptions, and take the first step toward a unified graph of organizational knowledge.
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Reproducing a One-Shot Launch — Engineering PayPay’s IPO Subscription Lottery/ Peihao Chen, Seiya Yazaki （Backend Engineer, PayPay Securities Corporation）
This session will explore how we designed a system that had exactly one chance to work: the subscription and lottery platform built for PayPay’s IPO. Distributing a primary offering of a US-listed stock in Japan was an industry first, and PayPay Securities was the only window for it — the timeline was fixed, the applicant volume was unpredictable, and the initial production launch was the only run. On top of that, a lottery returns a different answer every time. Discover how we made randomness reproducible by treating the seed as input, rebuilt the algorithm to fit an estimated hundreds of hours of computation into tens of seconds, and proved a non-deterministic system correct.
- 20:30-21:00
Networking
- This is a free, offline event held in a hybrid Japanese/English format.
- Reception is open from 6:40 PM to 7:00 PM. Please proceed to the reception desk on the 23rd floor of YOTSUYA TOWER within this time.
- Seating: Seating is limited. Please note that if the event is oversubscribed, participants will be selected by a lottery.
- Photography and Media: Please be aware that this event may be featured on the organizer’s blog or other media. Photos taken during the event may be used, but we will ensure that individuals are not personally identifiable.
- Privacy Policy: Personal information collected for this event will be handled in accordance with our privacy policy. Please review and agree to the policy on the application form before registering.
Please check the event form below for details and registration.
PayPay Developers Meetup in Tokyo