Senior Full-Stack Developer — React / TypeScript / Supabase / Shopify

We are seeking an experienced, startup-minded Senior Full-Stack Developer to assist with the development and launch of a confidential consumer-facing web platform. The application has already undergone significant development using modern web technologies and AI-assisted development tools. We are not starting from scratch. We need an experienced engineer who can evaluate the existing application, take ownership of the technical architecture, improve and complete the existing codebase, and help prepare the platform for production launch and future scale. For the right person, this has the potential to become a significant long-term engagement. Technology Environment Strong experience with several of the following is important: React TypeScript / JavaScript Supabase PostgreSQL Node.js REST APIs and webhooks Shopify / Shopify APIs GitHub Vercel or similar deployment platforms Authentication and user accounts Cloud storage Transactional email Responsive/mobile-first applications Third-party API integrations Experience with Lovable or similar AI-assisted application-development platforms is strongly preferred. Experience using modern AI development tools such as Cursor, Claude Code, GitHub Copilot, Replit, Lovable or similar tools is also highly desirable. Initial Assignment The first engagement will be a paid technical audit of approximately 10–20 hours. We want you to: - Review the existing codebase and application architecture. - Evaluate code quality and technical debt. - Review database architecture, permissions, and security. - Review existing third-party integrations and webhooks. - Evaluate the application's current use of AI-assisted development platforms. - Verify proper GitHub/version-control practices. - Identify unnecessary dependencies on third-party development platforms. - Recommend an architecture that gives the company full ownership and control of its application. - Identify security, performance, reliability, and scalability concerns. - Recommend what should be addressed before launch versus after launch. - Provide a practical development roadmap for completing the MVP. We are not automatically looking to rebuild the application. We want an experienced engineer who can determine what should be retained, what should be improved, and what—if anything—should be replaced. Who We're Looking For We want someone who thinks like a startup technical lead, rather than someone who simply waits for development tickets. You should be comfortable independently evaluating an application, identifying problems, recommending practical solutions, and executing those solutions. You must also be able to communicate technical decisions clearly to company leadership. We value: - Strong technical judgment - Speed of execution - Resourcefulness - Excellent communication - Ownership mentality - Practical solutions rather than unnecessary over-engineering - Comfort operating in an early-stage startup environment We are primarily interested in working with an individual developer, not a large development agency. Long-Term Opportunity If the initial technical audit is successful, we anticipate an ongoing development engagement of approximately 20–30+ hours per week. The right developer could ultimately assume substantial responsibility for the technical development and ongoing architecture of the platform. Confidentiality This is a confidential project. Additional information regarding the company, product concept, business model, business plan, detailed architecture, and proprietary functionality will be provided to qualified candidates only after execution of a Non-Disclosure Agreement (NDA). Please do not request confidential product information as part of your initial application. When Applying Please answer the following: 1. Describe your experience with React, TypeScript and Supabase/PostgreSQL. 2. Have you personally worked with an application built using Lovable? If yes, briefly describe your role. 3. Have you taken over an existing or AI-generated codebase? What did you do first? 4. Describe your experience integrating Shopify with a custom web application/frontend. 5. How would you determine whether an existing application should be improved versus partially or completely rebuilt? 6. Which AI development tools do you currently use? 7. Please provide examples of applications you personally developed and, where possible, GitHub examples. 8. What is your hourly rate? 9. How many hours per week are you currently available? 10. What time zone are you located in? Please begin your proposal with the words "FULL STACK" so we know you have read the complete posting.