John Kavanagh

Senior engineer for the first phase of the Nando’s UK/IE replatforming project, migrating the customer-facing estate from legacy Drupal to a modern, headless Next.js and Storyblok architecture. • Commercial Impact: Designed and implemented a comprehensive schema.org structured data layer (recipes, products, articles) that contributed to 349,000+ additional organic sessions and over £1.64m in organic off-prem revenue against the pre-migration baseline. • Architecture & Performance: Partnered with design to build a reusable block library mapping cleanly to Next.js components. Integrated Storyblok’s GraphQL API with aggressive caching and ISR strategies to drastically improve TTFB and mobile LCP. • Migration Strategy: Built extraction scripts and a "safe import" process to preserve legacy URLs and metadata, ensuring SEO equity and analytics remained intact during the switchover. • Operational Excellence: Proactively identified and mitigated critical blockers around Vercel caching and API limits to meet aggressive deadlines. Established clear documentation and FAQs that significantly reduced cross-functional friction between Engineering, SEO, and Design teams.

Contributed to the development and enhancement of an AI-driven data storage and compliance application, ensuring the successful rollout of a major release. • Release Management: Successfully prepared and launched a major application release by resolving ~25 priority bugs and implementing three new features ahead of the deadline. • Quality Assurance: Significantly reduced post-launch customer-reported defects compared to earlier releases, ensuring the application shipped on schedule with zero critical defects. • Performance Optimisation: Optimised application workflows, improving end-user performance in key compliance and data-retrieval tasks.

Returned to the Microsoft Redmond campus to steer a new strategic phase of the "Web We Want" initiative in collaboration with The World Wide Web Foundation. • Strategic Leadership: Led a team of external developers building in-browser extensions to improve developer workflows, resulting in positive industry feedback and recognition through presentations at W3C and Edge developer events. • Delivery: Delivered the "DevTools Issue Reporter" MVP 100% on schedule and executed a successful technical proof-of-concept, integrating AI-driven DOM analysis into the browser to automatically identify and remove distracting page elements. • Roadmap Strategy: Strengthened the product roadmap by prioritising direct browser integrations, resulting in hundreds of feature requests submitted monthly via the new channels.

Contract engagement delivered via James Chase. • Lead Engineer for the Digital First Browse team, responsible for the strategic replatforming of the airline's digital estate to a headless architecture. • Strategic Replatforming: Designed the migration of content-heavy pages to a modern Next.js architecture on top of AEM, moving from legacy monolith to headless to handle 4x concurrent traffic. • Business Impact: Delivered the new homepage in Q1 2023 with a 300%+ performance improvement (reducing load times from ~9s to <3s), driving a 12–15% uplift in booking conversion rates. • Scalability: Introduced a shared Storybook component library to unify the design system, reducing duplicate UI code by ~60% and cutting new feature development time by over 50%. • Technical Leadership: Led architectural direction for the critical Search and Booking flows, reducing search query response times from ~6s to ~1s to significantly decrease user abandonment.

Key technical role in the total re-platforming of a monolithic legacy e-commerce site into a modern, headless PWA. • Architecture: Shifted to a React-based Progressive Web App (PWA) consuming headless services from CommerceTools via AWS. • Scalability: Developed a reusable, white-label component library in Storybook, allowing rapid rebranding and deployment across other group properties (including Boohoo and Warehouse).

Partnered with a long-term collaborator to lead a specialist independent creative collective. • Technical Strategy: As Technical Director, I defined the agency’s engineering standards and "Front End Engineering Design" (FEED) workflows, bridging the gap between Figma-led design and production code. • Delivery Oversight: Orchestrated full-stack architecture and delivery for agency clients, specialising in bespoke Hybrid CMS solutions and modern React/TypeScript applications.

A specialised consultancy post working directly with the Microsoft Edge DevTools team on the "Web We Want" initiative, in partnership with the W3C. • Technical Leadership: Led a team of three external developers building solutions to identify and bridge gaps in web platform capabilities. • Tooling Development: Directed the development of in-browser extensions using TypeScript to enhance the developer experience. • Global Collaboration: Managed this role in parallel with other contracts, coordinating across time zones to align with the Washington-based engineering team.

Tasked with the modernisation of a massive, Dockerised monolithic platform with over eight years of legacy development. • Strategic Migration: Orchestrated the gradual roll-out of an all-new React-based front-end, reducing average page load times by ~35% (from 3.5s to under 2s) and cutting Time to Interactive by ~40%. • Feature Development: Delivered complex new features, including tiered forum membership structures and deep-dive Topic and Article pages. • Skills: React.js, GraphQL, Legacy Modernisation, Docker, Agile.

Senior role within a specialist team tasked with creating a scalable site-generation engine. • Scalable Architecture: Built a reusable component library using GatsbyJS (React & TypeScript) and Contentful to deploy approximately 12 distinct feature sites. • Client Empowerment: Engineered a "page-builder" architecture that allowed non-technical content creators to spin up new, branded sites rapidly without developer intervention. • Leadership: Managed architectural decisions, code reviews, and provided one-on-one mentoring to junior developers.

Strategic role focusing on the "Search & Browse" architecture of a major luxury e-commerce platform. • Legacy Unification: Tasked with bringing three distinct, historic codebases (Handlebars, Vanilla JS, SASS) together into a unified modern workflow. • Modernisation: Led the migration to a headless version of Adobe Experience Manager (AEM), replacing legacy front-ends with reusable React components and boosting Lighthouse scores from the mid-30s to high-80s. • Scale: Maintained high-traffic segments of the site while streamlining the deployment workflow, transforming updates into a simple single-developer task.

Architectural lead responsible for defining the platform strategy for a high-traffic, multi-brand e-commerce system. • Architecture: Designed the platform architecture and established a shareable component library to serve multiple international brand sites. • Tech Stack: Led the implementation using GatsbyJS (React & TypeScript) with Styled Components, connecting to a custom GraphQL middle-tier that aggregated data from Episerver and Contentful.

Frontend lead for an automotive CRM and customer-facing platform. • Scale: Architected and delivered a massive 10,000+ page Gatsby build, recognised as one of the largest successful Gatsby implementations at the time. • Quality Engineering: Established a component-driven workflow using Storybook and enforced rigorous end-to-end testing with Cypress. • Tech Stack: TypeScript, React, Styled Components, Gatsby.

Delivered a suite of high-performance static sites using the JAMstack architecture. • Tech Stack: Integrated GatsbyJS with a headless CMS (Contentful) and Eventbrite APIs. • Code Quality: Enforced type safety and modular styling using TypeScript and PostCSS to ensure maintainability for future teams.

Dual-track role managing a massive high-end e-commerce platform (160,000+ products) while driving a modern tech transition. • Strategic Rebrand: Led the UI development for the 2018 'John Lewis & Partners' ground-up rebrand, coordinating the visual overhaul across the digital estate. • Platform Evolution: Maintained and enhanced the existing legacy stack (Handlebars, SASS, AEM) while developing the all-new React-based platform. • Mentorship: Provided technical mentoring to junior developers, ensuring code quality and consistency across a complex codebase.

Client-facing Principal role for an experience-driven, multi-brand, and multi-lingual e-commerce platform built on Episerver. • Architectural Strategy: Ring-fenced the front-end workflow into a standalone Node.js/Gulp application to decouple it from the back-end release cycle. • Automation: Designed a build process that automatically generated deployed Razor templates and territory-specific stylesheets, ensuring consistency across multiple international regions. • Tech Stack: Utilised SASS (BEM/Atomic), Handlebars, Backbone, and Lodash to manage complex, large-scale UI requirements.

Leading a specialist UI team on a high-profile digital transformation project to rebuild the commercial banking platform. • Technical Leadership: Led the full-stack rebuild of the commercial banking application, architecting the middle tier with Node.js and the front-end with React and AEM. • Team Building: Directly accountable for team growth, personally sourcing and hiring five developers. • Engineering Standards: Professionalised the development culture by introducing pair programming, mandatory peer reviews, and rigorous test coverage using Jasmine.

Joined an early-stage fintech start-up to build their MVP using Angular 2 and SASS. The core challenge was integrating the front-end with a backend machine learning engine, visualising real-time data and analysis derived from massive datasets for the end user.

Joined the Style.com start-up team during the prototype phase, evolving the MVP into a complex, high-traffic e-commerce platform using Clojure. We integrated stock systems from hundreds of vendors. I also built a JavaScript/Clojure plugin that used AI to automatically link editorial content to relevant marketplace products.

Developed a multilingual e-learning platform using Google's Polymer framework and Web Components. The application ingested QTI data to render accessible, media-rich interactive templates, including quizzes, drag-and-drop functionality, and timed assessments.

Brought in to help transition the agency from print-based design to digital. I helped build and manage the new digital team while remaining hands-on, defining technical workflows and delivering several bespoke tourism e-commerce platforms and iOS app.

Sole UI developer for the complete rebuild of the BBC Homepage and the introduction of BBC ID. I consulted interdepartmentally to develop the 'four screens' responsive design guidelines, applying these learnings directly to the News and Weather sections. The new accessible-first homepage was nominated for the Design Museum's Design of the Year.

Part of an agile, multidisciplinary team developing the new Oxfam website and e-commerce platform (built on .NET and Episerver). My focus was on building high-traffic fundraising and campaigning journeys, ensuring robust accessibility and performance standards.

Joined the in-house team to refactor and optimise the front-end platform in preparation for internationalisation. I executed a ground-up rebuild of the template system and replaced the legacy search and filtering tools with a responsive, AJAX-powered alternative.

Sole Front-End Developer within the McCann Metro Innovation Labs. Responsibilities included maintaining websites for a major hotel chain and developing high-traffic social networking applications for the London 2012 Olympic Games. I handled the full lifecycle from Information Architecture (IA) and design to development, integrating accessible front-ends with WordPress and Cisco EOS.

Sole client-side developer responsible for the complete redesign and rejuvenation of the social networking platform. I rebuilt the front-end from scratch using xHTML Strict, integrating with a Django backend and AWS hosting. The relaunch significantly improved search engine rankings and user activity, leading to award nominations and a partnership with Guardian Sustainable Business.

Agency role creating pixel-perfect, validated xHTML and CSS templates for high-profile clients. I integrated front-end assets with CakePHP and CodeIgniter frameworks and managed the development and distribution of HTML email campaigns. The role required strict cross-browser compatibility testing and server load optimisation.

A diverse early-career role in this close-knit animation and production studio, requiring high versatility. Responsibilities included developing websites and Flash-based educational games for the BBC, alongside 2D/3D animation (Lightwave) and video editing (Avid) for broadcast. I also managed the company's IT infrastructure and Windows web servers, continuing the role remotely while completing my degree.

Occasional weekend safety car driver during open-track days for both cars and bikes.

Technical developer for this student-run project, developing and supporting an online social network for current, past and present placement year university students.