Full-Stack Engineer (Lead Product Engineer)

Type: Full-time | long-term independent contractor

Reports to: CTO

Location: Remote / (EST, CST) time zone

About the client
A marketing agency specializing in e-commerce growth and conversion optimization, they help brands streamline the customer journey to boost sales and lifetime value. Their services focus on improving site conversion, reducing cart abandonment, and increasing repeat purchases through targeted creative and technical strategies. With an emphasis on data-driven impact, they present clear metrics like higher conversion rates, more repeat buyers, and stronger LTV growth.

About the role
You're the one in charge to build and scale the first production version of our AI-powered Marketing Intelligence Layer for Shopify brands. You’ll turn prototypes into robust, secure, and fast web applications that integrate deeply with Shopify, Klaviyo, and future MarTech tools.

Responsibilities

• Design, develop, and maintain the main app (front-end + back-end)
• Integrate with Shopify Admin API, Klaviyo API, and future partner APIs
• Implement data ingestion flows and user authentication (OAuth 2.0)
• Build dashboards and insight views that deliver actionable recommendations
• Work closely with the CTO and AI team to implement API endpoints for LLM interaction
• Set up CI/CD pipelines, testing, and documentation

Requirements

Required Skills & Experience

• Frontend: React, Next.js (or Remix), TypeScript, TailwindCSS
• Backend: Node.js + Express or NestJS, PostgreSQL (via Prisma ORM)
• DevOps: Docker, GitHub Actions, AWS (Lambda, ECS, or Amplify)
• Integrations: Experience with Shopify GraphQL Admin API and Klaviyo REST API
• Data: Understanding of marketing KPIs (LTV, CAC, ROAS, retention)
• 3–5 years building production SaaS applications with multi-tenant architecture

Bonus: experience with Stripe Billing, auth0, or Supabase Auth

What Success Looks Like

• V1 of the product deployed to real Shopify stores
• <1s API response time for recommendations
• Stable connection with Shopify/Klaviyo even under heavy usage