Oskar Okuno

U-Next (Tokyo, Japan)

Senior Frontend Engineer

U-Next is one of Japan's biggest video streaming services. I work in a 15-person frontend organisation on the main site, video.unext.jp, and the Smart TV apps — in a team where most day-to-day communication happens in Japanese.

• Reviewed our GraphQL server's error handling and introduced forward-compatible errors, so a client that meets an error type it has never seen degrades to a sensible fallback instead of breaking. New server errors can now ship without waiting on every client to catch up.
• Proposed and built internal tooling with the data science team for the content metadata pipeline, replacing a manual spreadsheet step. It was my own initiative rather than assigned work, built with agent-driven development, and a team has depended on it weekly for business-critical data ever since.
• Ongoing work on the Smart TV apps across roughly 6 platforms, and a contributor to their migration off a PHP-rendered stack onto React. The living rooms are the constraint: TV browsers run years behind, so the build transpiles to an older ECMAScript target behind a substantial polyfill layer and hand-tuned webpack config.
• A heavy share of code review across the frontend codebase.

Japan also recalibrated how I work: the bar here is ship it right rather than ship it fast, and visibly caring about quality counts for as much as velocity.

Tech used: React (Next.js), GraphQL, Node.js, webpack, Docker, Github Actions, Nginx, Selenium, PHP

Tabist (previously Oyo Japan) (Tokyo, Japan)

Frontend Team Manager / Tech Lead

Tabist Oyo Japan is a hotel services company serving both guests and hotel owners. Their bookings all arrived through OTAs such as Rakuten Travel — there was no direct channel at all.

• Two of us built that channel: tabist.co.jp, where guests search hotels and book directly, plus a CMS so the business could run its own content, across separate integration, staging and production environments.
• I chose the architecture. Having watched enough projects collapse under their own weight, I optimised deliberately for simple and resilient over clever: Next.js and Fastify on AWS Fargate, Strapi for content, Terraform for the infrastructure, and Github Actions to ship it.
• Also shipped the companion iOS and Android app in React Native.
• Managed a team of 2 developers and owned hiring — 1–2 interviews a week — growing the team by 3 people.
• Planned the roadmap and negotiated priorities with the rest of the company.

Tech used: React (Next.js), React Native (iOS & Android app), Node.js (Fastify), Docker, AWS (Fargate), GCP, Github Actions, Terraform, Selenium, Strapi CMS

Asurion (Tokyo, Japan)

Tech Lead & React Native Developer

Asurion is an insurance company specialized in mobile phone insurance. I was working on several projects which introduced new consumer services, such as delivery service and insurance. My responsibilities were mobile app and website development. I worked closely with BAs, managers, designers and other developers. The main technology I used was React Native to create an iOS and Android app.

Tech used: React Native, Objective-C (iOS), Java & Kotlin (Android), React, Graphql, Node.js, Docker, AWS, Appium, Jenkins

Rakuten (Tokyo, Japan)

Tech Lead & React Native Developer

Rakuten Kobo is Rakuten's e-reading business. I joined as a consultant and later as an employee, as tech lead of the 5-developer team in Tokyo rebuilding the Kobo iOS and Android app in React Native, coordinating with a second team in Canada.

• The reader was the hard part. It was deeply entangled with the rest of the existing app, so lifting it into a new React Native codebase meant untangling those dependencies first — brownfield work with no clean seams anywhere.
• Coordination across the two teams was a bottleneck, so I designed an architecture that let Tokyo unblock itself instead of waiting on handovers across an inverted timezone.
• Brought the team to a regular QA release cadence, and worked directly with design and the PO to keep designs inside what React Native could actually deliver — far cheaper than discovering the limit at implementation time.
• Built the Appium test automation from scratch; Jenkins was already in place.
• Hired 3 developers into the team, interviewing 1–2 candidates a week.
• Fixed scroll performance for users with very large libraries — long vertical book lists were a genuine pain point, and a combination of approaches got it smooth.

Tech used: React Native, Objective-C (iOS), Java & Kotlin (Android), Docker, Jenkins, Appium

Fusion Systems (Tokyo, Japan)

Fullstack React Web/Mobile Developer

I worked in a team building a SaaS restaurant management solutions. My role was a fullstack developer and my focus was building frontend web applications using React. I was also building mobile apps with React Native. The backend was built with Java, Node.js and Python running on AWS with Docker. The work was organized in an agile fashion with Scrum as the main methodology. The role also included working on infrastructure managing EC2 instances and ECS docker containers.

Tech used: React, React Native, Objective-C (iOS), Java & Kotlin (Android), Java, Docker, AWS, Appium, Selenium, Python (Django)

Netlight (Germany)

Senior Consultant & Full Stack Developer

As a Netlight consultant, I was supporting clients on site with delivering software solutions by providing my technical and management expertise. The role was also to collaborate with sales to land new assignments and to mentor new recruits and support hr when hiring new talent.

Client	Description
Prosieben, Munich, Germany	Prosieben is one of Europe's largest media companies. They have several streaming platforms and I was working for one of them. I was hired because their media ingestion was using an inefficient third party monolith application. I was part of a team that was rewriting the monolith into microservices while trying to learn German. In the end we could speed up both the media ingestion and the metadata processing. Tech used: Node.js, Vue, PHP, Docker
Sixt, Munich, Germany	Sixt is one of the world's biggest car rental companies. I joined their frontend team to improve the team performance by introducing agile methodology and to transform their old PHP stack into a modern React/Go stack. During my time at Sixt we created a new frontend from scratch and improved communicating with other teams such as marketing and adwords teams. Tech used: React, Go, PHP, Docker, AWS
Fielmann, Hamburg, Germany	Fielmann is Germany's biggest optician. They were expanding their business in Switzerland and I joined to boost their productivity. I managed a team with 2 junior developers to improve the database migration. I was also working with the team that were adapting the whole application for use in Switzerland. We were using Agile methodologies by the book which was the first time I have experienced an organization fully invested in Agile, and it was working really well! Tech used: C#, Angular, MS SQL, Selenium, Docker

Relocation & German language school (Munich, Germany)

Moved from Sweden to Germany, took some time off, and went to language school to get to a level where I could work in German.

Mecenat (Gothenburg, Sweden)

Full Stack .NET Developer

Mecenat is an affiliate marketing company specialized in university students. It's the unofficial student identification in Sweden that gives you discounts in almost all shops in Sweden. I was working in the platform team that were managing the whole IT operation for the company. I took care of end to end, from frontend to network.

Tech used: ASP.NET (C#), MS SQL, Javascript

Around-the-world trip (everywhere)

Eight months travelling the world. Highly recommended.

Flex Applications (Örebro, Sweden)

Mobile Web Developer

Flex is building HR Solutions. I joined to replace the iOS app with a mobile web app for both iOS and Android. I successfully created the web app which replaced the need for a native app which better served the business.

Tech used: Javascript, jQuery Mobile, Objective-C, ASP.NET (C#)