Web App Development
Ecommerce Web App Development Beyond the Shopify Ceiling
When your store has outgrown off-the-shelf platforms, we build custom ecommerce web apps with the checkout flows, inventory systems, and B2B ordering portals your business actually needs.
When Shopify Stops Working and Custom Ecommerce Web App Development Begins
Shopify works until your business model stops fitting its assumptions. When you need custom pricing tiers by customer segment, a B2B ordering portal with net-30 terms, a subscription box with dynamic bundling logic, or a marketplace where multiple vendors share a storefront — you have outgrown off-the-shelf ecommerce. Custom ecommerce web app development is where bespoke engineering pays for itself: one custom build replaces three years of Shopify plugin subscriptions and the workarounds that slow your team down daily.
The ecommerce conversion funnel is unforgiving. A one-second delay in page load reduces conversions by 7%. A confusing checkout flow costs you 70% of cart abandoners. At Greta, we build ecommerce web apps that combine Next.js Incremental Static Regeneration for sub-200ms product page loads with custom checkout flows optimized for your specific buying journey — not the generic Stripe Checkout modal that looks identical to every other store on the internet.
Inventory management, returns processing, and order status tracking are the operational backbone that founders underestimate. These backend systems are what separate an ecommerce web app that is pleasant to use from one that scales to $1M in annual revenue. We build order lifecycle management — from cart creation through fulfillment and returns — into every ecommerce web app from the start, not as a phase two sprint when operational chaos forces the issue.
Our Approach to Ecommerce web app development
Every project follows our 4-step vibe-coding process — AI handles the boilerplate, senior engineers handle the craft. From idea to live product in 3–7 days for MVPs.
Discovery
We map your product catalog structure, pricing rules, customer segments, and fulfillment workflow before writing a line of code. We ask: what does Shopify not let you do that costs you revenue every week? That answer becomes the scope of what we build custom versus what we use Stripe Checkout for as-is.
Design
We design the full commerce UI: product listing pages with filtering and faceted search, product detail pages with variant selectors, cart with upsell logic, checkout with address validation, and order confirmation with tracking integration. We wireframe the admin order management view too — the side of ecommerce that rarely gets design attention.
Build
Next.js 15 ISR for product pages that update without rebuilds, Supabase PostgreSQL for inventory and order data, Stripe for payment processing and subscription management, and a custom admin panel for order management. AI-assisted development handles the CRUD scaffolding; our engineers handle the pricing logic, discount rules, and inventory sync.
Launch
We run a full payment flow test in Stripe test mode before go-live, validate inventory decrement logic under concurrent order load, and configure order confirmation webhooks for your fulfillment partner. We deploy to Vercel and monitor error rates and conversion metrics for the first week post-launch.
What You Get
Every ecommerce web app development engagement includes these deliverables — scoped before we start, delivered before we invoice.
- Product catalog with variant management, inventory tracking, and low-stock alerting
- Custom checkout flow with address validation, shipping rate calculation, and promo codes
- Stripe payment integration: one-time purchases, subscriptions, and stored payment methods
- Customer account portal with order history, returns initiation, and saved addresses
- B2B ordering portal with net terms, bulk pricing, and purchase order support
- Admin order management dashboard with status updates and fulfillment tracking
- Next.js ISR for product pages with sub-200ms load times and SEO-optimized markup
- Inventory sync webhooks for integration with 3PL or warehouse management systems
- Abandoned cart recovery logic with automated email triggers via Resend
- Vercel deployment with CDN optimization for product images via Next.js Image component
Tech Stack We Use
Our ecommerce web app development stack prioritizes page speed and data integrity. Next.js 15 with ISR ensures product pages are statically cached but revalidate on inventory changes, delivering fast page loads for customers and accurate stock data for the business. Supabase handles the relational data model — products, variants, orders, customers, and inventory — with PostgreSQL constraints that prevent overselling. Stripe processes payments with full PCI DSS compliance handled at the infrastructure level. We add Tailwind CSS for the storefront design, Vercel for global CDN deployment, and custom webhooks to connect your ecommerce web app with fulfillment partners, accounting systems, and marketing tools.
Case Study
FinTrack — Custom Financial Data Platform
FinTrack is a financial data aggregation platform built for a founder who needed a custom dashboard beyond what Plaid's generic UI widgets could provide. While not a traditional ecommerce build, FinTrack demonstrates our ability to handle complex data relationships, real-time updates, and transaction processing at scale — the same engineering challenges that define custom ecommerce web app development. We built FinTrack in 9 days: Supabase real-time subscriptions for live transaction updates, custom categorization rules stored in PostgreSQL, and a Stripe integration for platform subscription billing. The product processed its first $2M in tracked transactions within 45 days of launch.
Read full case studyPricing Transparency
Ecommerce web app development starts at $5,000 for a lean custom store with Stripe checkout, product catalog, and order management. Full builds with B2B portals, multi-vendor support, subscription boxes, and custom admin tooling run $15,000–$50,000 depending on catalog size and integration complexity. Shopify migration projects are scoped separately after a data audit. All projects include full code ownership, deployment configuration, and one week of post-launch support.
MVP
From $5,000
3–7 business days
Full Build
From $15,000
2–4 weeks
All projects include full code ownership, two revision rounds, Vercel deployment, and one week of post-launch support. No hidden fees.
Frequently Asked Questions
When should I choose custom ecommerce over Shopify?
When your business logic cannot be expressed in Shopify's data model: custom B2B pricing tiers, multi-vendor commission splits, subscription bundles with dynamic contents, or complex fulfillment rules. If you are spending more on Shopify apps than you would on a custom build, it is time to switch. We will be honest with you about which situation you are in.
Can you migrate my existing Shopify store to a custom web app?
Yes. We export your product catalog, customer data, and order history from Shopify and import it into the new system. The migration timeline depends on catalog size and whether you need custom URL structures for SEO preservation. We do not break your Google rankings during the migration.
How do you handle PCI DSS compliance for payments?
We use Stripe as the payment processor, which handles PCI DSS compliance at the infrastructure level. Your custom ecommerce web app never stores raw card numbers — Stripe handles tokenization and vaulting. This means you do not need a PCI audit, which would cost $15,000–$40,000 annually for a self-managed payment system.
Can you build a B2B ecommerce portal with net payment terms?
Yes. B2B ecommerce web apps require a different purchasing flow from consumer stores: quote requests, purchase orders, net-30 invoicing, and tiered pricing by account. We have built B2B portals with Stripe Invoice for payment terms, custom pricing rules per customer account, and a sales team admin view for managing B2B relationships.
How fast do ecommerce pages load?
Product pages built with Next.js ISR typically load in under 200ms for returning visitors, under 500ms for first visits, with a Core Web Vitals score of 95+ on PageSpeed Insights. Fast pages convert better — we treat performance as a revenue concern, not a nice-to-have.
Can you integrate with my fulfillment partner or 3PL?
We integrate with fulfillment APIs via webhooks. When an order is placed, a webhook fires to your 3PL's API to create a fulfillment request. When the 3PL ships the order, a return webhook updates the order status in your web app. We have integrated with ShipBob, ShipStation, and generic fulfillment APIs.
Do you build the product photography or content for the store?
No — we build the technical infrastructure, not the content. You supply product images, descriptions, and copy. We configure the image delivery system (Next.js Image with Cloudflare CDN) and the content management workflow, but the content itself comes from you or your team.
What happens when I need to add new product types or features after launch?
The codebase we hand over is fully documented and structured for extension. Adding product types means adding database rows and updating the admin panel — typically a one-to-two-day task for a developer familiar with the stack. We also offer retainer engagements for ongoing feature development after the initial build.
Ready to ship?
Ready to build your ecommerce web app?
Start Your ProjectOr reach us directly at hello@greta.agency
Written by the Greta Agency team · Last updated April 2025