Sean Matheson, Developer in London, United Kingdom
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Sean Matheson

Verified Expert  in Engineering

Software Developer

London, United Kingdom
Toptal Member Since
May 27, 2020

Sean's preferred role is to develop rich, engaging web apps utilizing React and Node.js. He enjoys writing modular, maintainable code—preferring simplicity over complexity. Details are important to him. Sean leverages agile techniques, design systems, layers of tests, succinct API design, and effective communication, considering DX/UX and working effectively within cross-functional teams to deliver high-quality products.



Preferred Environment

OS X, Neovim, Amazon Web Services (AWS)

The most amazing...

...thing I have developed is an open-source library by the name of Easy Peasy, a state management library for React that is continuously growing in popularity.

Work Experience

Senior Engineer

2019 - 2020
Fidelity International
  • Successfully launched a time-sensitive and critical feature allowing users of the system to review their investment portfolio and receive/accept new advice.
  • Introduced a design system and Cypress integration test-based development approach for developing new UI features in tandem to server development.
  • Dramatically improved the developer experience in regard to the development of the application. Spent a solid month unraveling complex technical debt, bringing down a 2-minute feedback loop to a couple of seconds.
Technologies: React, Node.js, TypeScript, JavaScript

Senior Engineer

2018 - 2018
News UK
  • Successfully built and launched the FIFA World Cup 2018 section for The Sun, a digital publication.
  • Worked efficiently and effectively to ensure that we built the FIFA World Cup 2018 in a manner that would be both scalable and dependable.
  • Introduced the foundations of a React-based server rendering layer to unlock the capability to use WordPress as a headless CMS.
Technologies: React, Node.js, JavaScript

Senior Front-end Engineer

2017 - 2018
  • Worked with a highly skilled team to migrate the checkout workflow from a legacy system into a robust server rendering React application that serves multiple brands (e.g. Topshop, Wallis, Burton, etc).
  • Built features allowing users to transport their basket of selected products from one region to another.
  • Dramatically improved the quality of analytics deployed across the application, unlocking critical information for business analysts.
Technologies: React, Node.js, JavaScript

Senior Engineer

2017 - 2017
The Gilt Club
  • Successfully built and delivered the entire server-rendered React application that was both responsive and progressively enhanced.
  • Developed high-quality adaptive UI elements allowing users of the system to perform complex calendar based interactions in a simple manner.
  • Worked closely with the designer to ensure the implementation was of the highest quality.
Technologies: Node.js, React, JavaScript

Senior Engineer

2017 - 2017
Friction Free Shaving
  • Completely rebuilt their existing application into a robust modern stack in order to address the technical constraints they were facing.
  • Worked closely with stakeholders and delivered a working prototype within a time-pressured requirement.
  • Recommended and implemented dramatic improvements for user experience in regards to the application checkout process.
Technologies: Node.js, React, JavaScript

Senior Front-end Engineer

2016 - 2016
  • Designed and developed a powerful React-powered CMS API allowing their developers to implement highly flexible implementations for their varying client needs.
  • Designed and built a React-based library allowing for element-based responsive design, allowing for the creation of components that are highly portable.
  • Implemented static type checking with automatic run-time type checking generation to ensure that code quality was adhered to for a very complex application.
Technologies: React, JavaScript

Lead Engineer

2008 - 2015
  • Worked within the product development team and was responsible for building multiple versions of their products and modules within their brand management ecosystem systems.
  • Introduced a custom module system allowing the development of fully encapsulated modules that could be easily plugged into any of the existing product deployments. Examples include REST APIs, storage engines, UI components, and security guards.
  • Introduced CI/CD. semantic versioning, TDD/BDD, pair programming, code reviews, agile development techniques, and strict guidelines to code quality and practices.
Technologies: .NET

Web Developer

2007 - 2008
  • Built a robust content management platform utilizing ExtJS.
  • Ensured scalability requirements were met via multiple layers of caching, including database, Memcache, application pool, and edge.
  • Built CMS in a modular fashion allowing adoption across various publishing groups.
Technologies: .NET

Web Developer

2006 - 2007
  • Worked in an extremely time-pressured manner for highly regarded brands.
  • Developed custom websites, web services, and management systems for extremely creative digital marketing projects.
  • Built web services to power Flash-based multiplayer games, video feeds, custom CMSs, gallery modules, user management, access modules, mail template management, product catalogs, fully managed content sites, etc.
Technologies: .NET

Junior Web Developer

2005 - 2006
  • Built an events management platform for an education-based organization.
  • Built a set of back-office tools and workflow management for a law firm.
  • Moved the organization from class ASP-based development onto ASP.NET.
Technologies: .NET

Intern Web Developer

2003 - 2004
  • Built a DNS parsing and management tool to aid support staff.
  • Researched and built multiple micro tools to support staff.
  • Worked with support staff to try and identify solutions to problems they were facing.
Technologies: Unix, Perl, PHP

Easy Peasy
Easy Peasy provides you with an intuitive API to quickly and easily manage the state for your React application. Batteries are included - no configuration is required to support derived state, API calls, performance optimization, developer tools, etc.

A React component library that allows components to become aware of their width and height. This opens up the opportunity for highly flexible and portable components. Storybook.js uses it internally, and it receives approximately 1.4 million downloads from the npm registry per week.

ComicKult Holding Page

ComicKult is a personal project. An attempt to create an engaging tool for the comic community that revolves around strong social tools and interaction. This is the holding page that I have created whilst I develop the actual implementation. It received an accolade from One Page Love.
2001 - 2004

Bachelor of Technology Degree in Information Technology

Cape Peninsula University of Technology - Cape Town, South Africa


Node.js, React, CSSinJS, React Redux


Git, Now, Webpack, Babel, Mongoose, Sketch


Express.js, Jest, Cypress, Next.js, Redux, .NET


TypeScript, JavaScript, GraphQL, HTML, CSS, PHP, Perl


Unit Testing, REST, Agile


Vercel, Firebase, Docker, OS X, Unix, Amazon Web Services (AWS), Visual Studio Code (VS Code)


PostgreSQL, MongoDB, MySQL


API Testing, Styled-components, APIs, TypeORM, Neovim

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