Hello, I'm
Phil Parsons.
Principal Engineer & Web Developer
I build high-performance web applications, lead front-end architecture, and create design systems that scale across global organisations.
what I focus on
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Web Components
Building reusable, framework-agnostic components using custom elements, shadow DOM, and modern browser APIs.
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Front-End Architecture
Designing scalable application structures with a focus on performance, maintainability, and developer experience.
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Performance
Optimising web applications for speed and efficiency through modern techniques and tooling.
Experience
With over 15 years in software engineering, I've led design system teams and front-end platform architecture at JPMorganChase, Legal & General Investment Management (LGIM), and TP ICAP, delivering component libraries and tooling that enable product teams to ship faster while maintaining brand consistency.
As a consultant, I've driven digital transformations for clients including Formula 1, BNP Paribas, IG Index, and British Gas — building real-time data platforms, analytics systems, and mobile applications used by millions.
View full profile on LinkedIn- 15+ Years Experience
- 3 Design Systems
- 4 Transformations
- 6 Financial Institutions
Open Source
I maintain several open source projects on GitHub, including web component libraries and developer tools.
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@boxslider
A zero-dependency, lightweight content slider with multiple transition effects for modern browsers.
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@parsonic
Standalone web components for common website patterns including copy-to-clipboard, share buttons, and theme switching.
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Isolating React component updates with useSyncExternalStore
Most React performance advice focuses on avoiding re-renders, but that's only half the story. The real cost often lies in reconciliation—React checking every component for changes even when they don't re-render.
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Optimising WebSocket connections with a SharedWorker
With a SharedWorker we can share a WebSocket connection across multiple browser tabs. Effectively managing connections to the SharedWorker can be tricky but these simple strategies ensure stable and efficient connection handling.
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Bundling design tokens for Lit web components
Building a design token pipeline that keeps component styles isolated and supports light-dark color schemes requires balancing automation with developer experience. This post demonstrates a Style Dictionary approach that exports JavaScript tokens for Lit elements that maintains CSS as the source of truth for styling.
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Building scrollable tabs with experimental CSS features
New overflow and positioning features coming to CSS are making it easier to build common UI patterns with minimal JavaScript. This post explores how to build scrollable tabs using features from the overflow module and anchor positioning draft specifications