Resume

(Updated 2024/08/21)

Personal Data

• Name: Kentaro Matsumae (@kenmaz)
• Mail: kentaro.matsumae@gmail.com
• SNS: Twitter / Facebook / github / Qiita / Hatena / Speaker Deck

Education

• Apr 1999 – Mar 2003 Kindai University, Japan / Bachelor of Software Engineering

Skills

• iOS Application Development (Swift, Objective-C)
• Web Application Development (Go, Ruby, PHP, Perl, Java, JavaScript, MySQL, Memcached, Redis, Q4M, etc…)
• Android application development (Kotlin, Java)
• Flutter Application Development (Dart)
• Machine learning program development (Python, Keras, Tensorflow)
• Server application development (Java)
• Development of development support tools (Java, VBA)
• Infrastructure (Linux, Sakura VPS, AWS)
• CI (CircleCI, Jenkins)
• Data analysis (SQL, Hive, Vertica, Pig, Big Query)

Presentations

• Merpay & Mercoin Tech Fest 2023 / Merpay iOS GroundUP App Migration
• iOSDC2021 / Hacking Tesla: Imagine Apple Car by iOS App developer buying a Tesla car to research and develop apps
• iOSDC2020 / Streamlining UIKit-based app development with Xcode Previews
• iOSDC2019 / How to build a mobile payment app
• try! Swift NYC 2018 / Super Resolution with CoreML(Long Version)
• try! Swift Tokyo 2018 / Super Resolution with CoreML
• iOSDC2017 / Let’s make an idol face recognition app with CoreML
• DeNA TechCon 2015 / Swift migration case study in Manga Box
• Recruit The Forefront of Smartphone UX (May 2012) / UX, Monetization, and Technology of Nico Nico Douga iOS App
• Nikkei BP Smartphone Spring 2011 (May 2011) / How to make the Nico Nico Douga iPhone app

Publications / Contributions

• Snapshot Code Generation from Xcode Previews / Mercari Engineering Blog
• Streamlining UIKit-based app development with Xcode Previews / Mercari Engineering Blog
• Smartphone Design Contribution on UX for smartphone applications (September 2012) / Gijutsu Hyoronsha
• Complete understanding of Java tools Co-authored / Nikkei BP Inc (March 2011)
• Learn from Zero - Latest Java - Programming Co-authored / Nikkei BP Inc (September 2009)
• “Learn Java Tools Slowly,” 12 articles in total (Dec. 2009 - Sep. 2010) / Nikkei Software, Nikkei BP
• “Learning Java slowly” series of 12 articles (May 2008 - June 2009) / Nikkei BP, Nikkei Software
• Eclipse Practical Development Introduction / Gijutsu Hyoronsha
• “Verification of Eclipse TPTP” Contribution (2006) / Nikkei BP, Nikkei System Construction
• “Web Application Development Basics with Eclipse” Contribute (2006) / IDG Japan JavaWorld
• “Aspect Oriented Development Fundamentals” Contribute (2006) / IDG Japan JavaWorld

OSS activities / Personal Projects

• S3XY Key Fob
  • Tesla Control App for watchOS/iOS
• SRCNNKit
  • Super-resolution library using CoreML
• AnimeMaker
  • Flip-book animation drawing and sharing service (140k MAU, 5k Posts/day)
  • iOS App (800,000+ Install)
  • Android app (3 million+ Install)
  • Web
• Momoclo member detector
  • Web application build to learn deep larning / computer vision / face detection
• Other iOS Apps
• OSS Contributions

Work Experience

Mercari Inc (Jun 2018 - present)

• iOS Application Developer for Mercari
  • Development of mobile payment function Merpay / Tech Lead(TL)
• Projects:
  • iD payment integration(Apple Pay In-App Provisioning) as Client Tech Lead
  • Bank account connection function as Client Tech Lead
  • QR code payment function (CPM/MPM) as Client Tech Lead
  • Searching for nearby stores with map UI (Google Maps SDK) as Client Tech Lead
  • Sending and receiving (money transfer) function as Client Tech Lead
  • My page improvement as Client Tech Lead
  • SwiftUI migration

Chompy Inc (Dec 2019 - Mar 2020 / Side Job)

• Development Flutter Application for Merchant.

DeNA Corporation (Apr 2013 - May 2018)

• Lead engineer for Manga Box development project.
  • iOS app development, API design, server side development
  • Log aggregation for service growth, function improvement, AB test implementation
  • Develop CI environment, research new technologies, etc.
• Technologies
  • Language: Swift / Objective-C
  • Tools: CocoaPods / SwiftLint / Fastlane
  • Data store: CoreData / MagicalRecord
  • Communication / API: AFNetworking / JSONRPC / Codable
  • Perl / Amon2 / MySQL / Memcached
  • Hadoop / Hive / Vertica / Python / Keras / Tensorflow

2018

• First view UI improvement AB test & gradual migration
• CoreML + super-resolution validation (20% rule)

2017

• Paid membership feature (IAP auto-renewal subscription)
• Comics Store UI renewal
• Main screen UI improvement AB test & migration (hamburger menu -> tabs, add favorite function, enhance search function, etc.)
• iOS11 support (Social.framework removed, iOS8 support ended), iPhoneX support, Swift3 migration
• Verification of automatic coloring of comic images by deep learning (20% rule)

2016

• Guest Login, Bookshelf UI renewal
• UniversalLink / AppSearch support
• iOS10 support (ATS support, iOS7 end of support, etc.),
• Optimization of data update process
• Started gradual migration to MVVM architecture.

2015

• Manga Box member registration and login functions (mail, SNS)
• In-app coin purchase (consumable IAP items) function
• Comics Store (paid comics sales) function
• iOS9 support, SWift2 migration

2014

• Overall design/iOS app development for Manga Box Indie
• Post-release functional improvement and stable operation
• Monetization through advertising SDK and in-house advertising, anti-cheat measures, cost reduction measures such as webp implementation
• iOS8 support, iOS6 support end

2013

• System design for the entire service, iOS prototype development and verification
• Design and development of iOS application and server side
• Initial release (2013/12), operational stabilization, en/zh support

Dwango Corporation (Jun 2009 - Mar 2013).

2012-2013

• Verification and development of new services for smartphones (not yet released)
  • Leader of a development team of 4 to 10 members.
  • Verified and developed a system for exchanging voice, images, and text in real time.
  • Technologies used: Objective-C, Ruby
• Nicholson iOS App Development
  • Leader of a development team of 4 to 6 members
  • Development and design of the iOS app “Nicholson” (2013/5 service termination)
  • Development of a server for posting audio recorded by the iOS app
  • Technologies used: Objective-C, PHP, Java, Redis, MySQL, Memcached, Solr

2010-2012

• Nico Nico Douga and Nico Nico Live Broadcast iOS App
  • Leader of a development team of 4 to 12 members.
  • Developed and designed iOS apps “Nico Nico Douga” and “Nico Nico Live Broadcast” (later integrated into a single app as niconico)
  • Development, design, and operation of API servers for the above apps (video information display, search, authentication, etc.)
  • Design and implementation of a server program that sends video taken with the iPhone to the server in real time, compresses it, converts it to RTMP, and delivers it to the delivery server.
  • Technologies used: Objective-C, Java, Google Guice, PHP, memcached, MySQL
• Nico Nico Douga HTML5 Player
  • Development and design of a video player compatible with iOS Safari and Andorid web browsers.
  • Technologies used: JavaScript, CSS, HTML
• NicoNico Cho-Kaigi 2012 Ticket Sales and Authentication System
  • Development of a QR code ticket sales website for Nico Nico Cho-Kaigi
  • Development of an iOS application that reads QR codes for authentication
  • Technologies used: Objective-C, PHP, memcaced

2009

• Development of NicoNico Douga Mobile Delivery Server
  • Implementation and maintenance of the video delivery server for Nico Nico Douga Mobile.
  • Technologies used: Java, PHP, Tomcat, MySQL, Memcached

Hitachi Software Engineering, Ltd (Apr 2003 - May 2009).

2008

• Product development and in-house operation of an enterprise SNS web application (Mar 2008 - Jun 2009)
  • Designed and developed an enterprise SNS web application built with Ruby on Rails.
  • Responsible for the design and implementation of the infrastructure and communication functions.
  • Technologies used: Ruby on Rails, JavaScript, HTML, CSS, Apache, MySQL, Linux, MeCab

2007-2008

• Java Consultant (Nov. 2006 - Feb. 2008)
  • Provided technical support for Java and Web applications for internal projects.
  • Developed in-house tools (e.g., a tool to generate code from DB specifications, a tool to embed log output processing in the entire source code from log specifications, and an in-house tool to automatically generate flow diagram diagrams from programs written in PL/SQL).
  • Research and application of technologies to achieve test automation using JUnit code automation tools.
  • Related technologies: Java, Struts, Eclipse, various WebAP servers, RDMS in general

2006

• Product development of debugging tools based on bytecode rewriting technology (October 2005 - October 2006)
  • Design and development of Eclipse plug-ins to support debugging and fault identification.
  • Mainly responsible for the design and implementation of the UI.
  • Technologies used: Java, Eclipse, SWT/JFace, EMF, Javassist

2005

• Product development of a source code generation tool for web applications (October 2004 - September 2005)
  • Eclipse plug-in that generates source code for Strust-based web applications from screen transition diagrams created in Visio.
  • Technologies used: Java, Struts, Eclipse Plugin, Autonomic Comupting technology

2004

• Library information retrieval system development (March 2004 - September 2004)
  • Industry-university cooperative project with a research institute.
  • I was in charge of the design and development of the batch program that stores the book information acquired from each library in the DB.
  • Technologies used: Java+Servlet+JSP, Websphere, DB2

2003

• Development, operation and maintenance of personnel and recruitment information management system (June 2003 - February 2004)
  • Design, development, operation and maintenance of an internal system to manage personnel evaluation and recruitment information.
  • Technologies used: Java+Servlet+JSP, WebLogic Server, MS SQLServer

Related articles

• Streamlining development of UIKit-based projects with Xcode Previews
• LT Speaker at try! Swift Tokyo 2018 & Trained CoreML models are now available
• I talked about CoreML at iOSDC2017
• DeNA insider’s explanation of “Manga Box” system structure and internal structure of iOS app
• What engineers really think when they drink - Manga Box
• Dwango engineers’ technician’s spirit that drives Nico Nico Douga
• Employee introduction article