Shipped for 20M+ users · 5 user segments including low-vision and foreign residents · Taiwan Ministry of Digital Affairs certified
- Scale
- 20,000,000+ users
- Taiwan National Public Service
- Mechanisms
- 24% → 18%
- Reducing missed prize redemptions
- Client-reported share of missed top-tier prize redemptions: about 24% before ship, 18% one month after launch—directional internal read, not a published MoF figure.
- Testing scope
- 88%
- Task success across ages
- Moderated prototype usability testing sessions with users 18–70+, including visually impaired participants, on scan, donate, and redemption.
Roughly 20 million people rely on this official app, yet only 2.8★ App Store ratings and broken flows were excluding elders, newcomers, and low-vision users.
Context and design goal
In Taiwan, retail purchases always come with a uniform invoice (統一發票), often paper with a lottery number and QR code. The Ministry of Finance cloud invoice / e-invoice ecosystem (電子發票) lets people store digital copies, bind a mobile carrier barcode (手機條碼) for automatic matching, scan paper receipts into the app, and claim or donate prizes.
Design goal: To redesign the information architecture, flow and UI to make those core jobs obvious and trustworthy for elders, newcomers, foreign residents, and low-vision users.
The Homepage
Users opened the app and couldn't find what they needed — five very different segments, all frustrated for different reasons.
Every group shared one first action: scan a paper invoice.
Scan became the primary CTA on open: large tap target, readable text label, fixed placement.
Prototype testing with the same participants validated the scan-first direction — strong positive responses across ages, especially seniors.
Pushback with external stakeholders: promo-first vs. what users actually open the app for
External stakeholders wanted the sustainability outreach zone to dominate on open.
Same home layout, two incompatible defaults: older and low-vision users wanted fewer modules and strong color for quick recognition; younger users wanted a denser dashboard.
I brought interview evidence into government stakeholder meetings — I understood their need to surface carbon-reduction messaging, but the data said job-first ordering had to win the first screen.
A customizable home: section visibility toggles in Settings.
Usability sessions across scan, donate, and redemption reached 88% task success — including visually impaired participants.
Login & authentication
Authentication was secure, but middle-aged and senior users kept forgetting their verification passwords.
Shipped biometric login and in-app password recovery — no more memorizing credentials or hunting one-time codes.
Guided Onboarding Setup
About 1 in 4 major lottery prizes go unclaimed — people forget to check, miss notifications, or never link a bank account for auto-transfer.
Guided onboarding: biometric setup → bank account for auto-transfer → notifications → cloud backup, each step explaining why it mattered.
One month post-launch, missed top-tier prize redemptions dropped from ~24% to ~18% (client-reported).
Handoff & engineering alignment
Handoff included three layers:
- API state matrix — Each flow mapped against account states and timing windows, so engineering knew which endpoint to hit per scenario.
- Screen reader annotation — VoiceOver focus order marked directly on screens.
- Component specs — States, empty copy, and error strings per component in the Figma library.
Figma files
Wireflows, page logic, and hi-fi mockups — hi-fi and page flow first, wireframes for IA and early logic.