Fullstack AI Developer

UpsellPlus 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.

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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.

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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.

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End-to-end feature development

• 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.

Shopify product development

• 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.

AI-powered product capabilities

• 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.

Reliability and engineering quality

• 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.

Product and customer judgment

• Understand why a feature matters commercially.
• Speak directly with customers when necessary to understand a problem.
• Work closely with the CTO, customer success team, and founder.
• Challenge unnecessary complexity and propose simpler solutions.
• Take responsibility for the customer outcome, not only technical completion.

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• You have repeatedly shipped and maintained fullstack web applications in production.
• You are strong in modern JavaScript or TypeScript development.
• You can work comfortably across frontend, backend, databases, APIs, and infrastructure.
• You have experience designing and integrating third-party APIs.
• You can independently investigate unfamiliar systems and solve ambiguous problems.
• You understand testing, monitoring, performance, security, and production operations.
• You use AI coding tools effectively while carefully reviewing and validating their output.
• You communicate clearly and document important technical decisions.
• You prefer ownership and execution over meetings and elaborate process.

Experience with Shopify, ecommerce, recommendation systems, experimentation platforms, high-volume event data, or production AI applications is a meaningful advantage.

This role is probably not for you if

• You want every task fully specified before beginning.
• You only want to work on the frontend or backend.
• You consider a feature complete when the code is merged.
• You optimize for lines of code or ticket volume rather than customer value.
• You use AI-generated code without understanding or validating it.
• You need a large product, QA, or infrastructure team around you to ship safely.
• You enjoy architecture discussions more than releasing software.

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Please submit your resume, LinkedIn profile, GitHub profile, portfolio, or any other work that demonstrates what you can build.

Please also answer:

1. What is the most substantial feature you personally owned from idea through production?
2. What parts did you build, and what measurable result did it produce?
3. Tell us about a production issue you caused or inherited. How did you diagnose and resolve it?
4. How do you currently use AI in your development workflow?
5. If you have worked with Shopify or ecommerce systems, briefly describe that experience.

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