Fullstack AI Developer

Upsell Plus helps Shopify brands increase their average order value and conversion rate through intelligent product recommendations and upsells.

More than 300 brands use our products across millions of orders. We are building toward an AI-powered conversion optimization system that can understand a store, identify revenue opportunities, and help merchants launch and improve offers.

We are a small engineering team. You will work directly with our CTO and have substantial ownership over what we build and how it reaches production.

We want to ship more high-quality product without creating unnecessary process or management overhead.

We are hiring a fullstack developer who can take a well-defined customer or business problem, work through the technical decisions with our CTO, and independently deliver the solution across the stack.

This is not a role for someone who only wants to implement isolated tickets. You will own complete features: understanding the problem, designing the solution, writing the code, testing it, releasing it, monitoring it, and improving it using real customer feedback.

Within your first 90 days, you will:

• Understand the product, architecture, development workflow, and critical customer journeys.
• Make a meaningful production contribution within your first 10 business days.
• Independently own and ship a scoped customer-facing feature within your first 30 days.
• Ship at least one substantial feature or product improvement within 90 days.
• Deliver production work with appropriate testing, monitoring, documentation, and rollback planning.
• Diagnose and resolve production problems without needing step-by-step direction.
• Use AI development tools to increase speed while maintaining engineering quality.
• Earn the team’s confidence that you can own an important product area from problem to production.

We value speed, but we do not define speed as writing code quickly. Speed means delivering useful, reliable software with minimal rework.

• Turn product requirements and customer problems into technical plans.
• Build complete features across frontend, backend, data, and third‑party integrations.
• Make pragmatic architecture decisions appropriate for a growing SaaS product.
• Break large projects into small, releasable increments.
• Review feature performance after launch and iterate based on evidence.
• Build experiences that operate reliably inside the Shopify ecosystem.
• Work with Shopify APIs, webhooks, themes, checkout extensibility, app extensions, and merchant data.
• Design around Shopify’s platform constraints and review requirements.
• Ensure features work across different themes, stores, markets, devices, and configurations.

Prior Shopify development experience is valuable, but exceptional fullstack engineers can learn the platform.

• Integrate language models and other AI services into real customer workflows.
• Build systems that turn store and performance data into useful recommendations.
• Evaluate model outputs for quality, reliability, latency, and cost.
• Design fallbacks and safeguards for imperfect AI behavior.
• Distinguish between a useful AI capability and an impressive-looking demo.

• Write clear, maintainable code.
• Add tests proportional to the risk and importance of the change.
• Improve observability, error handling, and production diagnostics.
• Participate in code review and help improve engineering standards.
• Investigate root causes instead of repeatedly treating symptoms.
• Protect customer data and consider security throughout development.

• Understand why a feature matters commercially.
• Speak directly with customers when necessary to understand a problem.
• Work closely with the CTO,…