TnS Platform Team, past, present, and future


This post is for Day 14 of Merpay Advent Calendar 2023.

Hi, I’m @ntk1000, Engineering Manager of the Mercari/Merpay TnS Platform Team.
You may be wondering, “Mercari/Merpay?” Yes, our team belongs to both Mercari and Merpay.
And what is TnS? TnS stands for Trust and Safety. Our mission is to provide our users with a safe and secure service experience.
In this article, I would like to explain why our team belongs to both Mercari and Merpay, what we are doing as TnS, and what we have been and will be doing.

Starting as an AML/CFT Engineering Team

When I became the EM in charge of this team almost four years ago, the team name was the Merpay AML/CFT Team.
AML/CFT stands for Anti-Money Laundering/Combating the Financing of Terrorism. Merpay is mandated to conduct anti-money laundering and counter-terrorism financing as a financial service. The main role of the team at that time was to realize AML/CFT functionality through engineering and to develop and operate it.
Specifically, as written in a blog post after the release of Merpay here, we worked on the Rules Engine and defining and developing various rules on top of it.

Renaming from AML/CFT to TnS Platform

Shortly after I became an EM on the AML/CFT Team, the COVID-19 pandemic hit, and the team switched to a remote working structure. As restrictions on offline activities, such as stay-at-home measures, expanded and continued, there was a more active shift toward online services, leading to the growth of Merpay. To limit the increase in fraud losses, the types of anti-fraud measures also became more extensive. For example, the Rules Engine, mentioned above, now includes not only AML/CFT but also an increasing number of rules to control chargebacks associated with credit card fraud. While the Rules Engine serves as an after-the-fact detection that monitors transactions over a certain period of time, we also built the new real-time detection system.
Thus, we renamed our team from AML/CFT to TnS (Trust and Safety) in conjunction with the Product organization in order to provide a broad anti-fraud solution in line with Merpay’s expansion: a safe and secure transaction experience for our users. At the same time, our team is responsible not only for the development of anti-fraud rules themselves, but also for the improvement and operation of the rule execution platform as the service expands, so we renamed our team “TnS Platform” as the team responsible for the anti-fraud platform.

TnS Platform Team Building!

Team Mission Statement

Along with the renaming of the team, we also established a mission statement and responsibilities.


  • Empower Mercari Group by providing an anti-fraud measure platform and achieve Mercari Group’s mission with safe and secure transactions


  • Expand and reinforce fraud prevention/detection features for product growth
  • Design and align to the industry standards and regulations
  • Keep improving security, scalability, and reliability

Looking back, I can say that we have certainly fulfilled these responsibilities. The fraud countermeasures we implemented were not limited to Merpay, but also included the services of Group companies such as Mercari and Mercoin. At the same time, to improve the security, scalability, and reliability of the system, we moved forward with several cloud migrations.

From Merpay Product/Engineering to a Company-wide, Group-wide Organization

Along with the expansion of the team’s responsibility, one of the changes has been the strengthening of collaboration with the various TnS-related teams. In order to cope with increasingly complex and fast-paced fraud, the teams involved in fraud countermeasures now share a common sense of the challenges and cooperate with each other under the same goal/OKR. Originally, our team was already in contact with the TnS Product Team and often worked together on development rules and examining fraud countermeasures, and the ML team, which works together as a system to prevent fraud and respond to new fraud trends. This structure made it easy for us to contact other teams like operator teams, data analysts, and risk management teams.
For example, the operator team, which monitors transactions, shares the status of fraud damage in near real-time. This allows Product/Engineering to respond to sudden changes in fraud trends.

The organization has grown into a Group-wide fraud countermeasure organization not bound by the company structure, together with the Mercari TnS Team, which had been working on fraud countermeasures for Marketplace. Although Mercari is organizationally divided into several companies and teams, the Mercari app is a single app. So this structure is currently in place to prevent any omission of fraud countermeasures due to the division of companies according to organizational structure.
As a result, Group-wide TnS is quite a huge organization. However, the TnS Program Team has organized a common framework for our roadmap, common goals, and many other areas, which has enabled us to align the perspective and steps of each team. To give one specific example, the cycle of sharing each team’s backlog, discussing common OKRs by managers, sharing the strategy internally (Quarter Review and Next Quarter Sharing), and passing it on to each team’s OKRs has been working well. I feel that this cycle has resulted in smooth decision-making.
We have TnS-related engineering teams assigned in Mercari, Merpay, and India, and we are strengthening mutual knowledge sharing and system collaboration. We’ve started knowledge sharing from introductions of each team, and now we have study sessions to expand our domain knowledge. As for system collaboration, for example, we are considering the use of our Rules Engine and real-time fraud detection system developed by our team for fraud countermeasures in the marketplace, and engineers from Mercari are also involved in the development of the Rules Engine.

In short, we are collaborating well without being siloed!

Knowledge Sharing Session at the India Bengaluru Office

Summary for the Future

This article is a brief history of our TnS Platform Team, explaining the changes in the scope of our roles and our collaboration with related teams. The process of working together across organizations and companies with the same goals required a lot of discussion among the managers, but I believe that we were able to move forward with the changes without friction.

As Mercari Group continues to expand its services, we expect fraud prevention to become more complex and sophisticated. Despite the uncertainties because of Mercari’s unique combination of services and the lack of precedents for fraud prevention, I believe this is a challenging and rewarding area.

As an Engineering Manager of the TnS Platform Team, I aim to provide safe, secure, and reliable services to our users and develop an engineering team that can lead fraud countermeasure platform in various areas developed by Mercari Group.

Thanks for reading!

We’re TnS Engineering Managers!


If you are interested in our TnS Platform, please check out the following articles by our team members! (I have already referenced several of them in this article.)

Tomorrow’s article will be by @tokuda109. Look forward to it!

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