E-commerce · B2B Multi Vendor Marketplace Mobile
MobylX
B2B mobile marketplace with Java/Spring Boot backend on AWS (ECS/Fargate, DynamoDB, S3, SQS, API Gateway), Shopify as.
The brief
Build a B2B mobile marketplace enabling verified buyers and sellers to trade electronic products (primarily smartphones) with real-time bidding, dual-registration/KYC, inventory management, lottery-based buyer rewards, and secure wallet-based transactions — all on top of Shopify as the commerce engine with a React Native mobile app.
What we built
A full-stack B2B mobile marketplace for real-time bidding and trading of electronics (initially smartphones/laptops). Delivered over 87 weeks:
- dual-role buyer/seller onboarding with KYC document upload and multi-provider OTP
- Shopify-backed multi-vendor product catalog with dynamic category/brand/model hierarchy and metafield-driven SKU attributes
- CSV-based bulk seller inventory upload via SQS + S3, later migrated to DynamoDB
- multi-seller order splitting, IMEI device tracking, OTP-verified checkout, race-condition-safe cart, and invoice generation
- in-app wallet with wire-transfer top-up, Pabbly/Google Sheets admin approval, and DynamoDB transaction ledger
- quarterly lottery/lucky-draw rewards engine
- tiered seller subscription plans with SAGA rollback
- R&D on a real-time bidding module (deferred post-V1)
- JWT Auth Service with RDS; and
- full AWS infrastructure with CI/CD, centralised logging, and pre-production security hardening.
Production application live on both iOS App Store and Google Play Store as of May 2026, with full buyer/seller onboarding, product catalog, cart/Buy Now checkout, multi-seller order management, wallet top-up/deduction, lottery rewards, subscription plans, invoice generation, and IMEI-based device fulfilment tracking. Separate Auth Service deployed; DynamoDB fully replacing S3 for orders and products; centralised logging and Lambda authorizers active in production.
Delivery timeline
How it was built, phase by phase.
8 workstreams across 87 weeks of operated delivery.
- buildWeek 1–87
Dual-Role Authentication & KYC Onboarding
Full buyer/seller dual-registration flow including OTP verification (Firebase, MiniOrange, D7 Network), email verification, document upload for KYC, account-under-review states.
Multi-factor, dual-role onboarding with KYC document review, OTP/email verification, and JWT-secured sessions deployed to production
React NativeFirebaseMiniOrangeD7 NetworkShopify GraphQLAWS API Gateway - integrateWeek 1–52
Shopify-Backed Multi-Vendor Marketplace Core
Entire product catalog, multi-vendor inventory, category/brand hierarchy, and Shopify integration layer including metafields, webhooks, Webkul multi-vendor plugin, and storefront/admin GraphQL APIs.
Functioning multi-vendor product catalog with brand/category/model hierarchy, dynamic SKU metafields, and admin bulk-upload tooling
Shopify Admin APIShopify Storefront GraphQLWebkul Multi-VendorAWS API GatewayJavaReact Native - buildWeek 3–87
Order Management & Multi-Seller Order Splitting
End-to-end order lifecycle covering draft orders, multi-seller order splitting, OTP verification before placement, order status tracking (buyer/seller/admin views), IMEI upload for fulfilment, invoice generation.
Production-grade order system with race condition guards, IMEI-based device tracking, automated invoice generation.
Shopify Draft Orders APIAWS DynamoDBAWS S3AWS SQSJavaReact Native - buildWeek 4–87
Wallet & Payment Management
In-app wallet for buyers: balance top-up via wire transfer receipt upload, 5% fee deduction, Google Sheets/Pabbly automation for admin approval, OTP-secured checkout deduction, wallet transaction history.
Full wallet lifecycle from top-up request to order deduction with admin approval portal, transaction history, and rollback-safe checkout flow
Webkul Wallet APIPabblyGoogle SheetsAWS S3AWS DynamoDBReact Native - buildWeek 7–52
Seller Bulk Inventory Upload & S3/DynamoDB Caching Pipeline
CSV-based bulk product upload for sellers via S3 presigned URLs, SQS-queued processing, scheduled cache refresh of product JSON on S3, and eventual migration to DynamoDB for read-optimized product/collection storage.
High-performance product/collection serving layer fully migrated from Shopify direct calls to DynamoDB-backed read path
AWS S3AWS SQSAWS DynamoDBAWS LambdaAWS API GatewayJava - deployWeek 7–87
AWS Infrastructure, DevOps & Cost Optimisation
End-to-end cloud infrastructure covering ECS/Fargate migration, API Gateway (REST→HTTP→NLB routing), Lambda authorizers, EC2 scheduling, Secrets Manager, CloudWatch/RUM logging, CI/CD pipelines.
Production-grade multi-environment AWS deployment with CI/CD, centralised logging, secrets management, and VPC-optimised DynamoDB access
AWS ECSAWS FargateAWS EC2AWS API GatewayAWS LambdaAWS EventBridge - buildWeek 16–60
Lottery / Lucky Draw Management
Quarterly order-value-based lottery system: ticket issuance, winner selection scheduler, coupon lifecycle (active/expired/closed), scratch card UI, and winner announcement notifications.
Live lottery/rewards engine tied to buyer GMV with automated winner notification and scratch-card mobile UI
AWS DynamoDBAWS LambdaShopify MetafieldsReact NativeJava - discoverWeek 19–22
Real-Time Bidding (RTB) Module R&D
Research and design phase for a real-time bidding engine to support the core B2B marketplace proposition; evaluated Firebase SDK, discussed bidding flows.
Architecture documented; RTB feature deferred to post-V1 roadmap
FirebaseShopify Draft Orders API
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