CardKeeper is a next-generation wallet platform that consolidates merchant member cards, e-money balances, and credit payments into a single app. Delivered on iOS/Android simultaneously with Flutter, it realizes a “know before you spend” experience through real-time balance updates.
To eliminate “carrying paper cards for each store, balance checks that require a store terminal, payment in a separate app, and scattered usage history,”E-money × member-card operator, together — built in-house from scratch in 11 months.
Provides e-money balance management and a member-card system for merchant networks in retail and services. With card issuance at the scale of hundreds of thousands and store POS integration, it supports merchants' promotion and loyalty businesses.
Previously a fragmented experience: paper member cards + balance checks on store terminals + credit-card payment in a separate app. Declining user engagement and lost sales opportunities for merchants constrained business growth.
Simultaneous iOS/Android development with Flutter; state management organized via the BLoC pattern. A robust payment foundation in PHP (Yii2-style), real-time balance with Redis, and instant usage reflection through push notifications. A safe validation flow that separates sandbox and production environments.