remindersync

ReminderSync - AI-Powered Cross-Platform Reminders. Never miss a task again. It is a beautiful, intelligent reminder app that works seamlessly across iOS and Android with powerful AI features.

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Inspiration

As a phone reviewer constantly switching between Android and iOS, Sam's reminder system would break every time he changed platforms. Water plants? Missed. Empty bins? Forgotten. YouTube uploads? Delayed. We were inspired by this real frustration—why should remembering basic tasks be platform-dependent? We set out to build the cross-platform reminder app that actually works the way Sam (and millions like him) need it to.

What it does

ReminderSync is an AI-powered reminder app that solves four critical problems:

  1. Custom Snoozing: Snooze for exactly 22 minutes (or any duration) directly from the notification—no app opening required
  2. Powerful Recurring: Set reminders hourly, every 3 days, every Monday, or any complex pattern you need
  3. True Sync: Dismiss a reminder on your iPhone, and it disappears on your Android tablet too—instantly
  4. Beautiful & Fast: Material 3 design with Gemini 3 Flash AI that understands "water plants every 3 days at 9am"

How we built it

  • Frontend: Flutter for true cross-platform (iOS + Android) with a gorgeous Material 3 UI
  • Backend: Python Flask API with SQLite for lightweight, reliable data storage
  • AI Brain: Google's Gemini 3 Flash with structured outputs for parsing natural language into perfect reminders
  • Notifications: flutter_local_notifications with custom actions (Snooze 5m, 15m, Custom, Done)
  • Monetization: RevenueCat for seamless in-app purchases—Premium (₦20,000/$12.50/mo), Pro (₦10,000/$6.25/mo), and credit packs (₦9,500/$6 for 25 credits, ₦8,000/$5 for 10 credits)
  • Sync Engine: Last-write-wins conflict resolution ensures your latest changes always win across devices

Challenges we ran into

Surprisingly smooth sailing! The Gemini 3 Flash API's structured outputs feature made natural language parsing incredibly reliable, and RevenueCat's SDK handled cross-platform payments seamlessly. Flutter's notification actions worked beautifully on both platforms. The only minor hiccup was timezone handling for recurring reminders across different regions, which we solved using the timezone package.

Accomplishments that we're proud of

  • AI that actually works: Our Gemini 3 integration correctly parses complex requests like "empty bins every Monday and Thursday at 7pm" into structured recurring patterns
  • Notification magic: Custom snooze actions work perfectly—press "Snooze 22m" and it just works, no app opening needed
  • Sync perfection: The conflict resolution algorithm ensures reminders stay consistent across unlimited devices
  • Beautiful UX: We didn't just build functional—we built delightful. The UI feels native and premium on both platforms

What we learned

  • Gemini 3 Flash's structured outputs are a game-changer for reliable AI parsing—no more hacky regex or prompt engineering
  • RevenueCat makes cross-platform IAP incredibly simple (literally 10 lines of code for both platforms)
  • Users LOVE natural language input—"water plants every 3 days" beats tapping through 5 menus
  • Proper sync is harder than it looks, but a good last-write-wins strategy with timestamps solves 99% of conflicts

What's next for ReminderSync

  • Location-based reminders: "Remind me when I'm at the grocery store"
  • Smart suggestions: AI learns your patterns and suggests reminders before you ask
  • Voice input: Speak your reminder instead of typing
  • Widgets: Quick-add reminders from home screen
  • Wearable support: Apple Watch & Wear OS with haptic snooze controls
  • Team reminders: Share reminder lists with family or roommates
  • Gemini 3 Pro upgrade: Even smarter context understanding for complex workflows

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