Klas Mellbourn, Developer in Stockholm, Sweden
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Klas Mellbourn

Verified Expert  in Engineering

Bio

A full-stack developer, Klas has worked professionally since 1994. For the last six years, he has worked at Klarna, where he has participated in developing their app from the start and is ranked third on the list of most commits to the Klarna app monorepo out of over 500 developers and three million lines of code in TypeScript. Klas has worked with React, React Native, and Node.js at Klarna and was one of the people who introduced TypeScript and GraphQL. He loves the challenge of freelancing.

Portfolio

FirstVet
React Native, TypeScript, Nx, Lerna, GitHub, CircleCI, Tailwind CSS, Redux...
Klarna
TypeScript, JavaScript, React, React Native, Front-end, Full-stack, Node.js...
H&M
AngularJS, JavaScript, TypeScript, Node.js, NPM, Webpack, Yeoman, Bower, Grunt...

Experience

  • JavaScript - 13 years
  • Git - 11 years
  • TypeScript - 10 years
  • React - 6 years
  • React Native - 6 years
  • Redux - 6 years
  • Node.js - 6 years
  • GraphQL - 4 years

Availability

Part-time

Preferred Environment

TypeScript, React Native, Front-end

The most amazing...

...thing I've done is being ranked third on the list of most commits to a monorepo with over 500 developers and seven million lines of code for a Klarna app.

Work Experience

Architect and Senior Developer

2022 - PRESENT
FirstVet
  • Architected the first React Native-based FirstVet app from the ground up. It is an internationally leading provider of app-based pet care.
  • Initiated and led the development of the app. Created the design and template for the app.
  • Orchestrated multiple teams in the modular development of this large-scale app.
Technologies: React Native, TypeScript, Nx, Lerna, GitHub, CircleCI, Tailwind CSS, Redux, Redux Toolkit, RTK Query, Storybook, Docker, APIs, eCommerce

Senior Full-stack Developer

2016 - 2022
Klarna
  • Developed a Klarna checkout as a web developer, app developer, and Node.js developer. The checkout is the web application of Klarna, which handles end-user payments for millions of users and thousands simultaneously worldwide.
  • Developed a Klarna app, which is the end user app with 150 million users on iOS, Android, and the web.
  • Introduced new technologies like TypeScript and GraphQL. I advocated for these, built prototypes, and developed the final implementation.
Technologies: TypeScript, JavaScript, React, React Native, Front-end, Full-stack, Node.js, RxJS, Most.js, Redux, Kubernetes, Helm, GraphQL, Mob Programming, Git, GitHub, Bitbucket, Jenkins, Visual Studio Code (VS Code), Redis, Docker, Amazon Web Services (AWS), Storybook, Jest, Ruby, NPM, Webpack, Lerna, SCSS, Test-driven Development (TDD), iOS, Android, MacOS, Scripting, Zsh, Splunk, Kanban, Remote Work, Chrome Extensions, Klarna, APIs, eCommerce

Web Architect | Developer

2013 - 2016
H&M
  • Created an SPA from scratch and led the development of this. Was the first developer in a team that grew to 40 developers.
  • Introduced Angular, TypeScript, Node.js and Git. Had to teach and spread knowledge of these technologies. Held many courses in Git.
  • Built a continuous deployment environment, including automated unit tests, integration tests, and code coverage of both JavaScript and .NET using Node.js, TeamCity, and Octopus.
Technologies: AngularJS, JavaScript, TypeScript, Node.js, NPM, Webpack, Yeoman, Bower, Grunt, Gulp, Karma, Protractor, Reactive Extensions, RxJS, jQuery, HTML, CSS, Sass, Less, Bootstrap, .NET, ASP.NET Core, ASP.NET MVC, ASP.NET Web API, Visual Studio, Git, TeamCity, Octopus Deploy, Test-driven Development (TDD), Windows Communication Foundation (WCF), ReSharper, Async/Await, NuGet, MyGet, Windows PowerShell, CI/CD Pipelines

Experience

Klarna App

http://app.klarna.com
An end user app with 150 million iOS, Android, and web users. I participated in the development of their app from the start, and I am currently in third place on the list of most commits to the app monorepo out of over 500 developers and three million lines of TypeScript code.

FirstVet

https://apps.apple.com/us/app/firstvet/id1349241101
A React Native-based app for pet owners to get online access to pet care, both information and virtual meetings with real veterinarians. I architected a technical solution for this app, including a choice of technologies, architecture, design patterns, test automation, continuous integration, and continuous deployment. Also, I orchestrated the cooperation of multiple teams so that they could work together on the large-scale development of this app. Finally, I actively participated in developing significant parts of the app.

RaySearch Laboratories

https://www.raysearchlabs.com/
An advanced cancer treatment system that analyzes the three-dimensional structure of organs in humans to optimize radiation treatment. I developed the graphical user interface (GUI) in a team that regularly delivered quality-controlled medical software to international customers.

Education

1989 - 1994

Master of Science Degree in Engineering Physics

KTH Royal Institute of Technology - Stockholm, Sweden

Certifications

SEPTEMBER 2016 - PRESENT

MCSA: Web Applications

Microsoft

Skills

Libraries/APIs

React, Node.js, RxJS, Reactive Extensions, jQuery

Tools

Git, GitHub, Helm, Bitbucket, Jenkins, NPM, Webpack, Lerna, Zsh, Splunk, Nx, CircleCI, Redux Toolkit, RTK Query, Fastlane, Yeoman, Bower, Grunt, Gulp, Karma, Visual Studio, TeamCity, ReSharper, NuGet

Languages

TypeScript, JavaScript, GraphQL, Ruby, SCSS, CSS, HTML, C#, Sass, Less

Frameworks

React Native, Redux, Jest, Tailwind CSS, Windows Presentation Foundation (WPF), .NET, AngularJS, Protractor, Bootstrap, ASP.NET Core, ASP.NET MVC, ASP.NET Web API, Windows PowerShell

Paradigms

Test-driven Development (TDD), Mob Programming, Kanban, App Development, Model View Presenter (MVP), Dependency Injection

Platforms

Visual Studio Code (VS Code), Docker, Kubernetes, Amazon Web Services (AWS), iOS, Android, MacOS, Web

Storage

Redis

Other

Web App Development, Klarna, APIs, eCommerce, Front-end, Computer Science, Full-stack, Most.js, Storybook, Scripting, Remote Work, Web Development, Chrome Extensions, Octopus Deploy, Windows Communication Foundation (WCF), Async/Await, MyGet, CI/CD Pipelines

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