Chargezen Engine
Shopify Subscription & Recurring Billing Infrastructure
01 / OVERVIEW
Project Brief
Chargezen is an enterprise e-commerce engine designed to orchestrate recurring subscription orders and automated billing portals directly inside Shopify stores, improving customer engagement and merchant cash flows.
Operational Fragmentation
Shopify merchants face high churn and checkout friction when setting up recurring subscriptions. Existing platforms redirect customers out of the store to complete orders, or struggle with complex replenishment calendars.
Unified Full-Stack Console
We designed a full-stack Ruby on Rails and React subscription module. Engineered with custom Shopify App Proxies, secure GraphQL endpoints, and Sidekiq background workers. This allows customers to manage billing schedules, swap items, and customize frequencies seamlessly without leaving the host store.
Recurring Billing Engine
Automated billing manager tracking customer intervals and processing transactions.
- Integrates Stripe subscription contracts and Shopify Billing API.
- Automates smart dunning emails and retries for failed card processing.
- Manages complex frequency schedules (weekly, monthly, custom).
Merchant Dashboard
Analytics console for Shopify administrators tracking MRR and cohort churn.
- Aggregates financial insights, active subscriber lists, and SKU metrics.
- Features low-latency search filters and exportable CSV ledgers.
- Displays MRR trends and customer lifetime value (LTV) cohorts.
Frontend
- React.js
- Tailwind CSS
- Shopify Polaris
- GraphQL Clients
Backend
- Ruby on Rails
- RESTful APIs
- Sidekiq Job Runners
Database
- PostgreSQL
- Redis Cache
- Active Record
Infrastructure
- Docker Containers
- Cloudflare Deployments
- Postman
- Stripe Webhooks
04 / ARCHITECTURE
Design Decisions
Sidekiq Job Orchestration
Configured Redis-backed Sidekiq workers to run daily billing checks, dispatch notifications, and sync inventory.
Shopify App Proxy Integration
Used proxy routes to inject customer subscription portal UI directly inside Shopify store liquid templates, bypassing iframe layouts.
05 / RETROSPECTIVE
Key Learnings
- Handling webhook retries from Shopify requires idempotent database triggers to avoid double-charging.
- Caching active subscriber configurations inside Redis drops portal load times below 200ms.