Please do not print this, save the trees

Kirill Korolyov | London, UK| Contract only


I build web applications with React, while focusing on accessibility, performance, developer experience, types, automation and design systems. I have experience leading teams, mentoring and hiring. I have worked predominantly on greenfield projects, but don't shy away from improving existing codebases. I am a fast and avid learner of new tools, patterns, programming languages and paradigms. I am a perfectionist by nature but I know how and when to think pragmatically. I continuously sharpen the saw and share my knowledge.

Curent stack of choice

HTML, CSS, JavaScript, React, Node.js, TypeScript, GraphQL, Next.js, Webpack, ESLint, Jest, Prettier, styled-components, Storybook, react-testing-library, git, Figma, CircleCI, Vercel


Frontend contractor at Web3 labs

January, 2020 to March, 2020

Development and support of two cryptocurrency explorer web applications. Technologies include React, REST, emotion.

Frontend contractor at Trainline

February, 2020 to March, 2020

Migration of Trainline's mobile and desktop web applications to Google Analytics with extensive test coverage. Technologies include React, Enzyme, Redux, redux-observable.

Frontend lead at Eurostar

November, 2018 to October, 2019

Support of Eurostar main website. In my first lead role I've inherited an older codebase and a team without any developers. My responsibilities included hiring and coaching, managing complex, sometimes incompatible expectations from a lot of stakeholders while reducing technical debt and increasing performance of the site. I've introduced regular dev-only meetings to discuss potential improvements to the code and process, 1-to-1 catchups to discuss impediments with individual developers, and facilitated continuous pair-programming and collaboration. I've pushed for a number of technical initiatives, including the new CMS (Sanity) and migration to the single page application model.

Frontend developer at Eurostar

November, 2017 to November, 2018

Development of packages booking platform for Eurostar. I've been with the project nearly from the start and worked in a close collaboration with the designer, UX and other teams. We've built a React SPA with GraphQL backend. Following successful launch, I've continued implementing new features and tightening integration with other parts of the business. Despite this being my first commercial React project, I have quickly learned advanced React patterns and gotchas and have been making sure our code doesn't fall behind. Capitalising on my strive for pixel-perfect design, our team has build a shared component library, it later became the basis for the company-wide design system (which I gave an internal talk on).

Frontend developer at Kayako

March, 2015 to January, 2017

Development of Kayako's frontend Ember app. By far the largest application I've worked on. I have joined the project from the start and, being the only constant team member in almost 2 years, have worked on pretty much every feature. I have learned to deal with frequently changing and incomplete requirements (often improving these requirements myself) and complex business domain. I kept improving overall quality of the codebase through refactoring, better abstractions, gradual migrations to new technologies, conventions and linters. Inspired by React and Elm, I've designed solutions for app's state and change management. Having worked a lot on simplifying, modernizing and modularizing our CSS code, I became a go-to guy for all questions related to styling.

Co-founder & developer at Squelo

June, 2015 to August, 2015

Development of a professional social network with React.js and Node.js.

Consultant at Concrete

November, 2014 to February, 2015

Architecture and development of a web application for the next generation of Concrete platform. Borrowing lots of ideas from Ember.js, Angular.js, as well as my previous experiences in Ericsson and Indigo, I've been responsible for designing a scalable and maintainable application architecture, which keeps developers away from writing spaghetti code and pushes towards creating isolated and reusable component-based code. I've also delivered a number of application features.

Consultant at CityHook/Indigo

February, 2014 to November, 2014

Web client for Indigo customers. My scope of responsibilities includes frontend and some parts of the backend. Designed as a single-page Angular.js application, the frontend is build using Webpack and Gulp.

Software Engineer at Ericsson

June, 2012 to September, 2014

Highly scalable client-side architecture evolving around a custom web framework. Originally designed as an upper layer of the new network management system, the framework is now being used by Ericsson teams worldwide.

My previous responsibilities included supporting web based application for visualizing correlated/aggregated network data with backend in Scala and Lift.

I have also worked on a prototype of a policy manager for self-optimizing networks which was created using an alpha version of the aforementioned framework.

Software Engineer at AssistUnion

January, 2011 to August, 2011

Tour operator information aggregator written in PHP and JavaScript. The goal was to collect information from multiple tour operators (such as destinations, prices, hotels etc.) and present it in a unified way, allowing user to perform search and compare similar tours from different operators.

I have also worked on a Model View ViewModel web framework written in Ruby.

QA/Developer at innoWate

July, 2010 to December, 2010

innoWate specializes in social network games production. I performed a variety of tasks, ranging from testing and game content administration to social network integration and Russian to English localisation. I have also created a set of internal tools to aid myself with these tasks.

Web Developer at Medialink

June, 2009 to March, 2010

Creation of 20 websites for the internal CMS using PHP, HTML, CSS and JavaScript.

Web Developer at Zero Zoom Zone

September, 2007 to October, 2007

I have worked in a small team developing online advertisement portal written in PHP, MySQL, HTML, CSS.

Open-source and non-commercial projects

All of my open-source software, as well as contributions to other projects, is available at The major ones are listed below:


foo_musicbrainz is a component for foobar2000 media player. It can tag files by fetching data from MusicBrainz. It is written in C++/ATL with a bit of preprocessor metaprogramming.

Techbikers website

Development of new functionality and maintenance of the existing codebase written in React.

Started in 2006. The goal behind the project is to preserve old video games released on optical media in the best way possible. The website essentially provides a database of checksums of optical media copies (“dumps”). A strong community has evolved around the website over the years, the new data is being added on a daily basis. is backed by PHP and MySQL. Note: the project is currently maintained by someone else.


M.Sc. in Applied Software Technology

Dublin Institute of Technology (Dublin, Ireland), 2011 to 2012

Got awarded "First place MSc in Applied Software Technology” plus a gold medal. Gave a series of math and programming tutorials for classmates.

B.Sc. in Electronic Engineering (Telecommunications and computer networks)

Transporta un Sakaru Instituts (Riga, Latvia), 2007 to 2011

Got awarded “Best student in Telecommunications and computer networks”.

Thesis: Developing a peer-to-peer network framework. Source code:

Erasmus Intensive Programme in developing open source system expertise in Europe

Helsinki Metropolia University of Applied Sciences (Espoo, Finland), March, 2010

Our team has developed a cloud render farm. Technologies used inlude Ruby, Sinatra, MongoDB, Blender.

International University exchange program “Erasmus”

University of Žilina (Žilina, Slovakia), February, 2010 to June, 2010

Online Education