Tatsuya Oiwa


Quartz membership

August 2018 - Present

Quartz membership is a paid subscription service launched in November 2018. I developed the first version of the membership and billing system, which is, as of September 2020, used by over 21,000 paid members and over 1 million free members. It supports credit card payments and Apple / Google Pay, as well as in-app purchases for iOS and Android apps (the Android app is unfortunately being discontinued in July 2020).

With this experience, I have extensive knowledge of the technical aspects of the subscription business, including payment platforms, subscription lifecycle, promotional strategies, currencies and security.

In addition to subscriptions, I’ve been working on a number of other fine-grained user experience improvements related to the membership, such as passwordless authentication with magic links and gifting.

The core technology stack of the backend system includes Java, Kotlin (server side), AWS (EC2, ECS, RDS, ElastiCache, SQS and many others), and third party payment APIs (Stripe, Google Play and iTunes Connect).


March 2018 - July 2018

NewsPicks is a social platform that enables users to discover, share and comment on business news. It was founded in Japan in 2013 and has since become the country’s most widely used business news platform. I’ve been working as a backend engineer for this ambitious startup since March 2018, helping them expand their services into the U.S. market.

It has been challenging to bridge the gap between two very different markets, cultures and organizations in Japan and the U.S., and to quickly localize a large and legacy backend codebase into a new business.

After reblanding NewsPicks to Quartz through mergers and acquisitions, I have led the integration of NewsPicks and Quartz’ backend systems.

The core backend technology stack of NewsPicks is Java, Spring and Hibernate, and of Quartz which I’m primarily inovoled with is Node.js and Apollo GraphQL.

Gilt Japan

June 2016 - Feb 2018

Coming soon...

Rakuten's Global Search Platform

December 2012 - May 2016

Coming soon...