QLess

Landing page
Your Cart
Checkout Portal
Select the store
Scan the barcode
QR code generated after paying
Scan the QR code at the door to checkout

QLess — Skip the Line, Shop Smarter

About the Project

What Inspired Us

Standing in checkout lines feels outdated in a world where almost everything else is instant. Americans spend 37 billion hours per year waiting in lines, which comes out to:

$$ \frac{37 \times 10^9 \text{ hours}}{330 \times 10^6 \text{ people}} \approx 112 \text{ hours/person/year} $$

That is nearly five full days every year spent waiting.

We asked a simple question:
What if checkout didn’t exist at all?

That question led to QLess — a mobile self-checkout system that lets customers scan items, pay instantly, and leave the store with a verified QR code.

What We Learned

Technical Skills

React Native + Expo for cross-platform mobile development
Stripe PaymentIntents and webhooks for secure payments
MongoDB + Mongoose for scalable data modeling
Time-limited QR verification to prevent fraud
Skia graphics for modern glassmorphism UI

Business Insights

Self-checkout is a \$100B+ market
Trust and verification are critical for retailers
Small delays scale into major inefficiencies

How We Built It

System Architecture

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│   Mobile App    │ ─▶  │   Backend API   │ ─▶  │    MongoDB      │
│ (React Native)  │     │  (Express.js)   │     │   (Atlas)      │
└─────────────────┘     └────────┬────────┘     └─────────────────┘
                                  │
                                  ▼
                         ┌─────────────────┐
                         │     Stripe      │
                         │   (Payments)   │
                         └─────────────────┘