Mark Dylan Cosca
Senior Full Stack DeveloperReact, Node.js, AI Agents & Headless Commerce
I build fast, reliable web products end to end, from high-traffic Shopify Plus and headless storefronts to full-stack apps and production AI agents.
Open to remote work · Overlaps with US Pacific, CET and AEST hours
About
Who I am
I'm a senior full stack developer with 9+ years of experience, specializing in TypeScript, React and Next.js products backed by Node.js and Python services, PostgreSQL and vector data, and production AI agents built with tool calling, retrieval and evaluations. I've spent 7+ years deep in Shopify, from Liquid themes and custom apps to Hydrogen since its early releases, and I've led high-traffic work such as Spanx, serving 10M monthly visitors at 99% uptime. I enjoy owning products end to end, from client scoping and codebase architecture to the team standards that keep delivery smooth, and I'm genuinely excited about bringing AI into real products in ways people can trust.
Selected work
Client case studies
Side projects
Products I've built and own end to end.
Other brands I've built for
What I do
How I can help
Full-stack products
Next.js and React frontends with Node.js/Express and Python services, PostgreSQL schemas, authentication, multi-tenant and role-based access, queues, background jobs and WebSockets.
AI agents & automation
Agents built with the OpenAI, Claude and Vercel AI SDKs, using tool calling, RAG with vector databases, structured outputs and evaluations, with human approval steps before agents act. Also MCP integrations.
Shopify Plus & headless commerce
Liquid and Online Store 2.0 themes, Hydrogen/Oxygen headless builds, custom apps (App Bridge, Polaris), Functions, Checkout Extensibility, multi-store and multi-currency setups, 3PL and multi-warehouse integrations.
Performance, CRO & tracking
Core Web Vitals and Lighthouse work, A/B testing with Intelligems and Convert, server-side tracking (Meta Conversions API, GA4, GTM), and CRM integrations (HubSpot, GoHighLevel, Klaviyo, Twilio).
Skills
Tools I use, and how
Recent Shopify Plus migrations
- checkout.liquid → Checkout Extensibility
- Scripts → Functions
- Pixels → server-side tracking
- Liquid → headless Hydrogen
Full Stack
- TypeScript
- JavaScript (ES6+)
- React
- Next.js (App Router)
- Remix
- Node.js
- Express
- Fastify
- NestJS
- Python
AI Engineering
- OpenAI SDK
- Claude SDK
- Vercel AI SDK
- Tool-calling agents
- RAG
- Vector databases
- Structured outputs
- Evaluations
- Human approval steps
- MCP
Data & Architecture
- PostgreSQL
- Supabase
- MongoDB
- MySQL
- Redis
- Multi-tenant & role-based access
- Microservices
- Queues & background jobs
- WebSockets
Commerce
- Shopify Plus
- Hydrogen & Oxygen
- Liquid
- Online Store 2.0
- Checkout Extensibility
- Functions
- Custom apps
- App Bridge & Polaris
- 3PL & multi-warehouse
- i18n & multi-currency
More skills (5 groups)Fewer skills
Integrations & Growth
- REST
- GraphQL
- Webhooks
- OAuth / JWT
- Stripe
- Klaviyo
- HubSpot
- GoHighLevel
- Twilio
- Meta Conversions API
- Server-side tracking
- GA4
- GTM
- A/B testing (Intelligems, Convert)
Performance & Quality
- Core Web Vitals
- Lighthouse
- Accessibility (WCAG, 508)
- Jest
- Vitest
- Playwright
- React Testing Library
- TDD
Mobile
- Kotlin (Android)
- SwiftUI (iOS)
- Ionic
- Quasar
DevOps & Cloud
- Docker
- GitHub Actions
- CI/CD
- AWS / GCP
- Vercel
- Netlify
- Cloudflare Workers & D1
- Sentry
- Logging, monitoring & backups
Leadership & AI Tools
- Codebase architecture
- Scoping & estimates
- Team standards
- Code review
- Mentoring
- Claude Code
- Cursor
- GitHub Copilot
Experience
The road so far
Form Factory | Software Engineer (Full-time)
Sep 2022 – Sep 2026
Agency delivering Shopify Plus, headless and custom web builds for global brands such as Spanx, Turtle Beach, Solo Brands and Corza.
- Led architecture and delivery of high-traffic storefronts and web applications for global brands, scoping work directly with clients and owning it through to production.
- Delivered key Shopify Plus upgrades end to end, including checkout.liquid to Checkout Extensibility, Scripts to Functions, browser pixels to server-side tracking, and Liquid themes to headless Hydrogen builds.
- Built full-stack products and AI agents with Node.js, Python, PostgreSQL and vector search, using tool calling, retrieval, structured outputs and evaluations, with human approval before agents act.
- Drove CRO development and A/B tests that lifted conversion and average order value, and shortened build and deploy times through CI/CD improvements.
- Set coding standards and codebase architecture for the team, reviewed code, mentored developers, and delivered several projects solo from first commit to launch.
MindArc | Frontend Developer (Full-time)
Oct 2021 – May 2022
- Customized existing Shopify themes and built custom Liquid themes, plus fast React and Vue storefronts for global brands.
- Built custom Shopify apps and connected stores to Node.js services and third-party REST APIs.
Digital Studio / LiveCrossing | Software Engineer (Full-time)
Mar 2019 – Oct 2021
- Led development of a storefront on a custom e-commerce platform, built with PHP/Laravel and Vue.js.
- Took features from architecture through to release, working on both the frontend and backend.
Skubbs Inc | Web/Mobile Developer (Full-time)
Jul 2018 – Mar 2019
- Developed responsive websites and hybrid mobile apps using WordPress, Vue.js, Ionic and Quasar.
Fullmoon Outdoor | Developer (Full-time)
Jul 2017 – Jul 2018
- Developed websites and custom WordPress themes with HTML, CSS, JavaScript and PHP, and handled on-site SEO.
Informatics College Northgate | Bachelor of Science in Information Technology
Jun 2014 – May 2017
Certifications | Verify on Credly ↗︎
- Shopify Apps Development
- Liquid Storefront
- Headless at Shopify for Developers
How I work
Ownership, end to end
Client scoping
I scope work directly with clients, turn requirements into technical plans and estimates, and own delivery through to production.
Codebase architecture
I set the architecture for multi-store and multi-brand platforms, like five Turtle Beach stores and three Solo Brands storefronts on one codebase each.
Team standards & code review
I set coding standards for the team, review code and keep conventions consistent so delivery stays smooth.
Mentoring
I mentor developers through code review and technical documentation that makes large codebases easier to onboard into.
Solo delivery
I've delivered several projects solo, from first commit to launch.
Reliable pipelines
CI/CD, test coverage and AI-assisted workflows that shorten build and deploy times and keep releases predictable.
Contact
Let's work together
Looking for a senior full stack developer? I build fast, reliable web products end to end, from high-traffic Shopify Plus and headless storefronts to full-stack apps and production AI agents. I'm open to remote work, and the best way to reach me is by email.
