# E-Commerce App Development > App369 builds custom e-commerce platforms and mobile shopping apps with Shopify, Stripe, and conversion-optimized checkout. Canonical: https://app369.com/service/ecommerce-development/ A website for your business that takes orders and payments. App369 builds custom e-commerce platforms and [mobile shopping apps](https://app369.com/service/mobile-apps/) with Shopify integration, Stripe payments, and conversion-optimized checkout flows that turn browsers into buyers. [**Get Started **→](https://app369.com/contact/) What Simon builds ## **E-Commerce Development Services** 01 ### **Custom E-Commerce Platforms** Fully custom e-commerce solutions built with modern frameworks and headless architecture. Simon builds product catalogs, checkout flows, and admin dashboards tailored to your business model, from direct-to-consumer brands to multi-vendor marketplaces. 02 ### **Shopify Customization** Simon builds custom Shopify themes, private apps, and headless storefronts using the Storefront API for brands that want Shopify's backend reliability with a fully custom frontend experience. 03 ### **Payment Gateway Integration** Payment integration with Stripe, PayPal, Apple Pay, Google Pay, and regional payment methods. Simon implements 3D Secure for fraud prevention. 04 ### **Inventory Management Systems** Real-time inventory tracking across multiple warehouses and sales channels with automated low-stock alerts, purchase order generation, and barcode/SKU management. Inventory syncs with Shopify, Amazon, and custom fulfillment providers. 05 ### **Order Fulfillment Systems** Automated order processing from purchase to delivery with real-time tracking, shipping label generation via ShipStation or EasyPost, returns management, and customer notification emails at every stage of the fulfillment pipeline. 06 ### **Analytics & Conversion Dashboards** Custom analytics dashboards tracking revenue, conversion rates, average order value, customer lifetime value, and product performance. Simon integrates Google Analytics 4, Mixpanel, and custom event tracking to identify optimization opportunities. How it works ## **The process** 2. 01 ### **Market Research & Strategy** Simon analyzes your target market, competitors, and revenue model to define the optimal e-commerce architecture, whether Shopify, headless commerce, or fully custom, along with payment, shipping, and inventory requirements. 3. 02 ### **UX Design & Conversion Optimization** Simon designs conversion-optimized shopping experiences with intuitive product browsing, streamlined checkout flows, and mobile-first responsive design validated through user testing. 4. 03 ### **Platform Development** Simon builds your e-commerce platform with product catalog management, payment integration, real-time inventory tracking, order management, and Algolia-powered search with faceted filtering. 5. 04 ### **Testing & Security Audit** Comprehensive testing including payment flow testing with Stripe test mode, load testing for traffic spikes, and cross-browser/cross-device QA. 6. 05 ### **Launch & Marketing Setup** Simon deploys your store, configures analytics and conversion tracking, sets up email marketing automation for abandoned cart recovery, and integrates with social commerce channels. 7. 06 ### **Growth Optimization** Ongoing A/B testing of checkout flows, product page optimization based on analytics, inventory system scaling, new payment method integration, and feature additions driven by customer behavior data. Technologies - Shopify - Stripe - Vue.js - Node.js - Firebase - Algolia Questions ## **Frequently asked questions** ### **How much does it cost to build an e-commerce app?** Cost depends on scope, platforms and integrations. App369's rates are published on the fee structure page, and the free app cost calculator gives a range for an e-commerce app with every assumption listed. Simon sends a fixed quote after reviewing your brief. ### **Should I use Shopify or build a custom e-commerce platform?** Choose Shopify if you need a proven platform with built-in payment processing, inventory management, and a vast app ecosystem, ideal for launching quickly. Choose custom if you need unique checkout flows, complex product configurations, multi-vendor marketplace features, or full control over the tech stack. App369 also builds headless Shopify storefronts using the Storefront API for the best of both worlds. ### **What payment gateways do you integrate?** App369 integrates Stripe for credit card and ACH payments, PayPal for buyer-protected transactions, Apple Pay and Google Pay for one-tap mobile checkout, Shopify Payments for Shopify stores, and regional payment methods as needed. Simon implements 3D Secure for fraud prevention. ### **How long does it take to build an e-commerce platform?** A Shopify store with custom theme takes 4-8 weeks, a custom e-commerce website with product catalog and checkout takes 3-5 months, and a full marketplace platform with vendor management, real-time inventory, and mobile apps takes 6-12 months. App369 uses agile sprints to deliver functional increments every 2 weeks. ### **What mobile commerce trends should I consider?** App369 builds mobile-first e-commerce experiences optimized for these trends. ### **What features should my e-commerce app include?** App369 implements all of these as standard features. ## **Prefer a fixed price?** Fixed scope, fixed price, paid upfront. The work happens in writing; no call needed. - [**Shopify Speed & Checkout Tune-Up**$750Mobile speed and cart-to-checkout fixes on a duplicate theme, measured before and after.](https://app369.com/fixed-price/shopify-speed-optimization/) ## **Data and research** - [**App369 Client Review Data 2026**](https://app369.com/statistics/app369-client-review-data-2026/) The public Fiverr reviews, counted: returning buyers, where they are and what they bought. Start here ## **Start Selling Online Today** Whether you need a custom storefront or a [Flutter-based mobile shopping app](https://app369.com/service/flutter-development/), get a detailed estimate by email, usually within one business day, or book a consultation ($100 per 15 minutes, paid upfront). [**Get in touch **→](https://app369.com/contact/) [**View pricing**](https://app369.com/fee-structure/) Fiverr reviews / 28 on Shopify work ## **What buyers said about this kind of work** [**Read 126 of the 127 reviews **](https://app369.com/reviews/) - - - ### **Read the whole story** - [Four Shopify reviews in under three months, then an app](https://app369.com/case-studies/fiverr/shopify-store-repeat-orders/) (Rachel, Canada)