Nhan N.

I build and ship Shopify apps that pass App Store review. I have 3 public apps live on the Shopify App Store that I built solo, end to end (Withly Inbox, Withly Profit & Withly Cart Rules): embedded admin (React + Polaris + App Bridge), OAuth, Billing API, Admin GraphQL, Shopify Functions, webhook pipeline, GDPR compliance webhooks, queue workers, and self-managed Docker infrastructure. I have already cleared the review requirements and edge cases most developers get stuck on. My newest app, Withly Cart Rules (launched November 2026), runs on Shopify Functions: it blocks checkout when a cart line is below a minimum order quantity or not a multiple of the case-pack size, and applies quantity-tier discounts per product or variant. What I can help with: - Public or custom Shopify app development - React Router/Remix, TypeScript, Node.js, Prisma, Postgres - Expiring offline access token migration - required for every public app by January 1, 2027. If your Dev Dashboard shows an API health warning, this is why. The hard part is not the OAuth callback, it is background jobs and queue workers that use offline tokens outside the request lifecycle. - Shopify Scripts to Functions migration - Scripts were switched off on June 30, 2026. Any store still relying on them has dead discount, shipping, or payment logic right now. I have shipped checkout validation and discount logic on Functions in my own public app. - Shopify Functions, app extensions, Admin GraphQL, webhooks, billing - Deployment and hosting for Shopify apps - Docker, Postgres, Redis, queue workers, self-managed VPS. If your app needs infrastructure and not just code, I handle both. - Overflow capacity for agencies and app developers I also deliver production web apps for Japanese clients at my day job, so I am used to precise requirements across time zones. Tell me what is breaking or what you need built, and I will tell you exactly how I would approach it before you hire me.