John O.

Senior full stack developer with 4+ years building e-commerce systems that make money, not just pages that ship. I work at the intersection of Shopify engineering, conversion optimization, and AI enabled development, and I am usually brought in when a store has outgrown its theme, its data, or its team's capacity. Shopify, from Liquid to headless. I build and refactor Shopify themes (Liquid, Online Store 2.0, metafields and metaobjects), custom apps against the Admin and Storefront GraphQL APIs, checkout extensibility, and headless storefronts on Hydrogen and Next.js. I have migrated stores from Magento and custom PHP platforms onto Shopify Plus without losing SEO equity or order history. I know where Shopify's limits actually are, and when the right answer is a native feature instead of six weeks of custom code. CRO and analytics architecture. Redesigns without measurement are guesses. I set up the full loop: GA4 with a clean event taxonomy, server side tagging through GTM, enhanced e-commerce tracking that survives checkout, and A/B testing infrastructure that produces decisions instead of dashboards. Recent work includes an experimentation program that lifted checkout conversion 18 percent and a data layer rebuild that finally reconciled ad platform numbers with actual Shopify revenue. AI integration that survives production. I build LLM features with the OpenAI and Anthropic Claude APIs, LangChain, and RAG pipelines including GraphRAG over product catalogs and support content. That means product discovery assistants, automated merchandising copy with human review workflows, and support deflection bots grounded in real store data. I care about evals, cost per request, and failure modes, because a demo and a production AI feature are different projects. Performance as a feature. Core Web Vitals work that moves rankings and conversion together: render blocking cleanup, image pipelines, third party script audits, and edge caching. I have taken themes from failing CWV to green across the board. Stack: TypeScript, React, Next.js, Node.js, NestJS, Laravel, PHP, React Native, GraphQL, REST, PostgreSQL, MongoDB, Firebase, Docker, AWS, Vercel. Comfortable owning Figma to production end to end. I write code other developers can maintain, I document decisions, and I communicate in plain language about tradeoffs and timelines. If you need someone who can architect the system, build it, measure it, and iterate on the numbers, let's talk.