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Senior JavaScript/TypeScript developer with 20+ years’ experience delivering enterprise web applications across government, retail, insurance and technology. Specialising in React, Next.js and modern frontend architecture, I lead teams, modernise legacy platforms and deliver greenfield products with a strong focus on quality, maintainability and accessibility (WCAG 2). I’m comfortable mentoring while staying hands-on, collaborating with stakeholders to ship high-quality digital experiences. I also support automated testing and developer tooling (Storybook, unit/integration/E2E) and bring a pragmatic, contractor mindset to delivering value quickly.…Senior JavaScript/TypeScript developer with 20+ years’ experience delivering enterprise web applications across government, retail, insurance and technology. Specialising in React, Next.js and modern frontend architecture, I lead teams, modernise legacy platforms and deliver greenfield products with a strong focus on quality, maintainability and accessibility (WCAG 2). I’m comfortable mentoring while staying hands-on, collaborating with stakeholders to ship high-quality digital experiences. I also support automated testing and developer tooling (Storybook, unit/integration/E2E) and bring a pragmatic, contractor mindset to delivering value quickly.

Darren Sweeney

Web Developer, Front-End Developer, Programmer, +2

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Senior JavaScript/TypeScript developer with 20+ years’ experience delivering enterprise web applications across government, retail, insurance and technology. Specialising in React, Next.js and modern frontend architecture, I lead teams, modernise legacy platforms and deliver greenfield products with a strong focus on quality, maintainability and accessibility (WCAG 2). I’m comfortable mentoring while staying hands-on, collaborating with stakeholders to ship high-quality digital experiences. I also support automated testing and developer tooling (Storybook, unit/integration/E2E) and bring a pragmatic, contractor mindset to delivering value quickly.…Senior JavaScript/TypeScript developer with 20+ years’ experience delivering enterprise web applications across government, retail, insurance and technology. Specialising in React, Next.js and modern frontend architecture, I lead teams, modernise legacy platforms and deliver greenfield products with a strong focus on quality, maintainability and accessibility (WCAG 2). I’m comfortable mentoring while staying hands-on, collaborating with stakeholders to ship high-quality digital experiences. I also support automated testing and developer tooling (Storybook, unit/integration/E2E) and bring a pragmatic, contractor mindset to delivering value quickly.

Available to hire

Senior JavaScript/TypeScript developer with 20+ years’ experience delivering enterprise web applications across government, retail, insurance and technology. Specialising in React, Next.js and modern frontend architecture, I lead teams, modernise legacy platforms and deliver greenfield products with a strong focus on quality, maintainability and accessibility (WCAG 2).

I’m comfortable mentoring while staying hands-on, collaborating with stakeholders to ship high-quality digital experiences. I also support automated testing and developer tooling (Storybook, unit/integration/E2E) and bring a pragmatic, contractor mindset to delivering value quickly.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Beginner

Language

English

Fluent

Work Experience

JavaScript Developer at OneStream

January 1, 2025 - May 31, 2026

Developed features using Next.js, Sanity and Tailwind. Improved CMS functionality for content creators and increased code consistency across the website through frontend refactoring.

Senior React Developer at CGI – Home Office

May 1, 2024 - July 31, 2024

Developed React components for the TIOMS law enforcement reporting platform. Improved Cypress automation and accessibility compliance. Collaborated with Java backend teams to align frontend APIs.

Senior JavaScript Developer at UI Creatives

February 1, 2024 - November 30, 2024

Delivered multiple greenfield projects using Next.js and Sanity CMS. Introduced React Testing Library with Jest. Created reusable frontend patterns and a company-wide style guide. Built lightweight Node/Express APIs and data mocking solutions.

Lead Frontend Developer at Adder

June 1, 2022 - December 31, 2023

Led the migration from legacy JavaScript to React and TypeScript. Introduced Storybook and automated unit testing. Mentored developers and improved engineering standards across the team.

Head of Digital Delivery at Pinnacle Pet Group

October 1, 2018 - June 30, 2022

Led the organisation’s digital transformation of its frontend platform. Managed a multidisciplinary development team and delivered digital products for Sainsbury’s, Argos and the Post Office. Drove adoption of React, Agile practices and improvements to UX.

Lead Frontend Developer at Veolia

October 1, 2017 - October 1, 2018

Built asset management software used across major French cities. Introduced ES6 standards, code reviews and automated testing.

Lead Frontend Developer at Thales

February 1, 2016 - October 31, 2017

Led frontend development for TfL’s 4LM programme. Delivered a large-scale JavaScript application using RequireJS and MVC architecture. Achieved high unit test coverage and established development standards.