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Hi, I’m William James Johnston, a lead full-stack developer with 7+ years of experience building and optimizing eCommerce experiences using Shopify, Shopify Plus, and WordPress. I specialize in CRO-focused front-end and back-end development, performance optimization, and API integrations. I thrive in cross-functional teams, mentoring developers, and delivering scalable, headless architectures with Next.js and React. I love turning complex requirements into robust, maintainable solutions and driving measurable business results.…Hi, I’m William James Johnston, a lead full-stack developer with 7+ years of experience building and optimizing eCommerce experiences using Shopify, Shopify Plus, and WordPress. I specialize in CRO-focused front-end and back-end development, performance optimization, and API integrations. I thrive in cross-functional teams, mentoring developers, and delivering scalable, headless architectures with Next.js and React. I love turning complex requirements into robust, maintainable solutions and driving measurable business results.

William James Johnston

Web Developer, Front-End Developer, Full Stack Developer, +3

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Hi, I’m William James Johnston, a lead full-stack developer with 7+ years of experience building and optimizing eCommerce experiences using Shopify, Shopify Plus, and WordPress. I specialize in CRO-focused front-end and back-end development, performance optimization, and API integrations. I thrive in cross-functional teams, mentoring developers, and delivering scalable, headless architectures with Next.js and React. I love turning complex requirements into robust, maintainable solutions and driving measurable business results.…Hi, I’m William James Johnston, a lead full-stack developer with 7+ years of experience building and optimizing eCommerce experiences using Shopify, Shopify Plus, and WordPress. I specialize in CRO-focused front-end and back-end development, performance optimization, and API integrations. I thrive in cross-functional teams, mentoring developers, and delivering scalable, headless architectures with Next.js and React. I love turning complex requirements into robust, maintainable solutions and driving measurable business results.

Available to hire

Hi, I’m William James Johnston, a lead full-stack developer with 7+ years of experience building and optimizing eCommerce experiences using Shopify, Shopify Plus, and WordPress. I specialize in CRO-focused front-end and back-end development, performance optimization, and API integrations.

I thrive in cross-functional teams, mentoring developers, and delivering scalable, headless architectures with Next.js and React. I love turning complex requirements into robust, maintainable solutions and driving measurable business results.

Skills

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Expert

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Intermediate

Work Experience

Senior Software Engineer (Shopify Focus) at Streamily

July 1, 2020 - March 31, 2022

Customized Shopify themes and implemented feature updates using Liquid and front-end technologies. Managed large product imports and structured catalog updates. Implemented multi-currency functionality and region-specific store front adjustments. Optimized checkout flows and improved overall store performance.

Shopify Developer at Blue Switch

May 1, 2018 - June 30, 2020

Built and maintained Shopify stores for small and mid-sized brands. Assisted with store migrations and structural updates. Configured shipping logic, promotional pricing, and discount rules. Supported ongoing updates to product data and content.

Lead Full Stack Developer at Self-employed / Freelance (Shopify & WordPress Projects)

March 2, 2022 - Present

Lead Full Stack Developer for DTC Shopify and WordPress stores. Focused on CRO, performance, and scalability. Built and maintained custom themes, private apps, and plugins using Liquid, PHP, REST APIs, and PostgreSQL-backed services. Contributed to Next.js-based front-end components for headless Shopify experiences and marketing landing pages. Implemented analytics, A/B testing, speed optimizations, and checkout enhancements. Mentored developers and oversaw code quality, architecture, and deployment workflows. Built integrated solutions using Shopify Admin API, Storefront API, webhooks, and custom backend services. Contributed to headless Shopify architectures using Next.js and React for high-performance frontends.

Senior Software Engineer at Seamly.com

July 1, 2018 - June 1, 2020

Developed and customized Shopify and Shopify Plus themes for U.S.-based consumer brands. Built Angular-based admin and internal tools integrated with Shopify APIs. Worked with MongoDB and PostgreSQL for handling product, user, and transactional data. Integrated third-party apps and services to automate marketing, CRO, and analytics.