Full-Stack Developer To Finalise SaaS Project

We run a web and marketing agency and need a senior full-stack engineer to help us finish and launch an almost-complete SaaS-style platform called Trade Seekers for a client in the trades industry. The project has been in development for around two years and is close to launch. We need someone who can quickly understand an existing codebase, tighten it up, put proper testing in place, and drive it across the finish line to production deployment. Tech stack and experience required: - React and Next.js - Supabase (Postgres, SQL, Row Level Security) - Google OAuth authentication and general low-level security best practices - Stripe payments, subscriptions, webhooks and APIs - Working with APIs and webhooks (consuming and creating) - GitHub (pull requests, code review, branching) - Basic CI/CD (Vercel) - Automated testing (unit and integration) and structured manual QA What you will do: 1. Review the existing Next.js and Supabase codebase and propose a concise plan to get to production in about four weeks Set up a sensible testing approach for core flows such as signup, login, Google OAuth, payments and core app actions 2. Harden Supabase RLS policies and the authentication flow to prevent common security issues 3. Debug and finalize Stripe flows including payments, webhooks and error handling 4. Clean up and refactor critical areas of the app for stability with targeted fixes rather than big rewrites 5. Prepare and execute production deployment (likely Vercel plus Supabase), including environment variables, build setup and a rollback plan 6. Provide clear documentation for handover, including README, environment configuration and deployment steps Engagement details: 1. Fixed-price project 2. Expected timeline is approximately one month of focused work 3. Prefer at least 3 to 4 hours overlap with New Zealand business hours for standups and reviews 4. Potential for ongoing maintenance work if collaboration goes well What success looks like: - All core user flows tested and passing - No critical authentication or RLS security gaps in Supabase - Stripe working reliably in test and live modes - Stable production deployment with a documented process - Client can start onboarding real users confidently Requirements: - 3 or more years building real-world applications with React and Next.js - 1 or more years using Supabase (including SQL and RLS) in production - Hands-on experience implementing Google OAuth in Next.js Shipped at least one project with Stripe payments and webhooks - Comfortable working in an existing codebase and leaving it cleaner than you found it - Strong written English and proactive communication