Coupon Design and Constraints

About This Article

Coupons issued through point conversion have constraints to prevent fraudulent use. This article explains coupon specifications and their design rationale.

Basic Coupon Specifications

Characteristics of Issued Coupons

Coupon Code Format

Format: [Last 5 digits of customer ID]-[Random 6 characters]-[Point amount] Example: 70934-AB12CD-500

Benefits: Content visible from code, no duplicates, easy inquiry handling, difficult to generate fake codes

Constraint Details

Usage Count Limitation

At point conversion: 500pt consumed → 500 yen coupon issued

Customer-Specific Constraint

Shopify coupon settings:

customer_selection: "specific"
prerequisite_customer_ids: ["12345"]

Verification Flow

Customer enters code

Enter coupon code on checkout screen

Shopify checks

Is code valid? → Yes / Is this customer eligible? → Check customer ID

Result

Match → Apply discount / Mismatch → "This code cannot be used"

Validity Period Design

Expired handling: Expired coupon → Cannot use, Consumed points → Not returned, Advance reminder → Under consideration

Fraud Prevention Measures

Anticipated Fraud and Countermeasures

Brute Force Prevention

Code format: 70934-AB12CD-500

Brute force difficulty:

Even at 100 attempts/second, testing all patterns takes ~240 days
Plus rate limit of 60/minute

Additional measures: Temporary account lock on consecutive failures, detect abnormal patterns and alert

Conversion Rate and Limits

Points to Amount Conversion Rate

Base rate: 1 point = 1 yen

Future extensibility:

Campaign: 1pt = 1.5 yen
Member rank: Gold = 1pt = 1.2 yen
Design to be configurable

Conversion Limits

Customer Display

Coupon Information Display Items

Usage Instructions

Coupon Usage Guide

Add items to cart

Add products you want to purchase to cart

Proceed to checkout

Go to checkout screen

Find coupon code field

Look for coupon input field on checkout screen

Enter or paste code

Example: 70934-AB12CD-500

Click 'Apply'

Apply the coupon

Confirm discount applied

Subtotal: 5,000 yen → Coupon: -500 yen → Total: 4,500 yen

Benefits of This Design

Security

Minimize fraud risk
Limit damage even if issues occur
Traceable design for easy problem identification

Customer Experience

Clear, easy-to-understand amounts
Copy function reduces input effort
Sufficient validity period for stress-free use