E-commerce engineering services Checkout that survives
its own edge cases
Faizan Amir builds e-commerce systems around settlement, refunds, subscriptions and catalogue integrity. The work includes an eight-layer payment guard, dual settlement paths that protect paid orders, and Royal Mail despatch with tracking written back to the order.
What this includes
Immediate confirmation records the payment; a webhook then reconciles it. Either path can recover if the other is delayed.
Signature, ownership and amount checks combine with idempotency, replay protection and monotonic order status.
CMS-managed merchandising uses typed contracts and defensive rendering, so campaigns change without a release.
Catalogue scope is derived from host and market, then enforced again at checkout.
Carrier APIs generate labels and return tracking to the order, removing manual fulfilment steps.
How the work runs
- *[01]
Model the order
Define order states and transitions for settlement, refund, cancellation and renewal.
- *[02]
Assume events lie
Design for duplicate, late and mismatched events, then test those cases directly.
- *[03]
Separate the services
Separate storefront, transactional API and CMS ownership so content changes cannot take down checkout.
- *[04]
Connect fulfilment
Connect labels, tracking and operational views to the order lifecycle.
- *[05]
Watch the funnel
Track checkout success, reconciliation accuracy and promotion conversion from launch.
Where this has been built
WisdomUp
Multi-Service E-Commerce Platform
* IN DEVELOPMENT
Three deployable services with dual settlement, eight payment guard layers and 14 focused settlement tests.
READ THE WISDOMUP CASE STUDY →Volumize
Telehealth E-Commerce Platform
Telehealth commerce connecting intake, clinical approval, prescriptions, Stripe payments, Royal Mail despatch and renewals.
READ THE VOLUMIZE CASE STUDY →
[STACK]
- Next.js
- Express 5
- MongoDB
- Payload CMS
- Stripe
- Redux Toolkit
- RTK Query
- Zod
- Royal Mail API
Questions about e-commerce engineering
Shopify fits standard catalogues and checkout. Custom engineering is justified when the order includes clinical approval, market-specific catalogues or subscription rules the platform cannot model cleanly.
Idempotency and a unique transaction index stop duplicates. Immediate confirmation plus webhook reconciliation prevents lost orders, while monotonic status rejects stale events.
Yes. Volumize generates Royal Mail labels and writes tracking back to the order, keeping fulfilment and payment in one lifecycle.