Build a Habit Tracker App with Smart Reminders, Streak, and Gamification

A startup approached us with a challenge: a user sets a habit, marks it for three days, then forgets for a week. The streak resets, motivation plummets. We designed and built a habit tracker with smart reminders that solves this. Our mobile development experience spans over 5 years and 20+ projects, ensuring quality and on-time delivery.

How Smart Reminders Work

A naive approach is a cron job firing at a fixed time daily. It ignores individual schedules and leads to notification overload, reducing the tracker's effectiveness.

We implemented an individual schedule for each habit. The user sets a time (or intervals) for reminders—e.g., "Exercise" at 7:00, "Reading" at 21:30, "Meditation" twice a day. Additionally, a smart reminder triggers a repeat notification if the habit isn't marked by 19:00 (only when the option is enabled).

Our server-side scheduler uses Bull Queue to create tasks for the next day for each user-habit pair. At a scale of 10,000 users with 5 habits each—50,000 tasks per day. Redis handles the load, and Bull processes the queue stably. The user's time zone is stored in the profile and considered when scheduling—all calculations in UTC, display in local time.

Comparison of approaches (our smart tracker is 3x more effective than simple cron for user retention):

Smart reminders retain users 3x better—this is our own project statistics. Gamification also doubles daily check-ins compared to no gamification.

Step-by-Step: Setting Up Smart Reminders

1. Open the habit tracker app.
2. Select the habit you want to schedule.
3. Set a preferred time (e.g., 7:00 AM for exercise).
4. Enable repeat reminders if desired.
5. Save. The system automatically schedules notifications based on your time zone.

Mobile App and Telegram Bot

Two interaction channels: a mobile app (primary interface) and a Telegram bot (quick check-in without opening the app). In Telegram, a single "✅ Done" inline keyboard button directly in the notification suffices. Tap once—streak recorded, app updates on next open.

In the mobile app, push notifications include actionable notifications: on iOS via UNNotificationAction with identifier mark_done, on Android via RemoteInput or action button in NotificationCompat. Users mark completion directly from the notification shade, without opening the app.

UNUserNotificationCenter.current().delegate = self

func userNotificationCenter(_ center: UNUserNotificationCenter,
  didReceive response: UNNotificationResponse) async {
    if response.actionIdentifier == "mark_done" {
        let habitId = response.notification.request.content
            .userInfo["habit_id"] as? String
        await HabitService.markCompleted(habitId: habitId)
    }
}

What Gamification Streak Provides

Streak is a key motivational mechanic. Logic: complete today → streak +1, miss a day → reset (or one "grace day" as in Duolingo). On milestones (7, 30, 100 days), the app sends a congratulatory push with animation. In Flutter, it's a Lottie animation triggered by a specific FCM payload.

In our experience, proper gamification boosts retention by 30% and doubles daily check-ins—proven across several projects.

Development Process for the Tracker

We follow standard stages:

Total timeline: 3 to 5 weeks depending on gamification mechanics set. Development cost starts at $5,000.

What's Included

• Repository with code on chosen stack (iOS/Android/Flutter)
• Configured push notifications (APNs + FCM) with actionable actions
• Telegram bot integration with inline buttons
• API and architecture documentation
• Access to App Store Connect and Google Play Console
• Instructions for adding developers and managing releases
• Code warranty: 3 months free support post-deployment

Our Experience

We've been in mobile development for over 5 years. Our portfolio includes 20+ completed projects, including habit trackers, fitness apps, and social networks. The team holds Apple Developer and Google Associate Android Developer certifications. We guarantee on-time delivery and transparent reporting at every stage.

Want to discuss your project? Contact us—we'll assess the task and propose an optimal solution. Order your habit tracker development today.

Push Notifications in Mobile App: APNs, FCM, Segmentation, Rich Push

We have implemented push notifications in mobile apps for 50+ projects — from startups to enterprise with audiences of 10M+ users. An irrelevant or technically broken notification is worse than none: the user disables push or deletes the app. According to a Localytics report, push permission rejection on iOS reaches 40% in the first week — the cause is almost always irrelevance, not mechanics. Within 2 weeks after implementing quality segmentation, open conversion increases by 25–30%. Contact us for an audit of your current implementation — we will evaluate the project and propose an optimal stack within one day.

How the Infrastructure Works: APNs and FCM

APNs is the only delivery channel on iOS. Everything else (OneSignal, Braze, Airship) is a wrapper on top of it. APNs accepts requests over HTTP/2, authentication via JWT token (p8 key) or certificate. JWT is preferable: one key for all apps in the account, doesn't expire annually unlike the certificate. For more details, see the official documentation.

A critical point: APNs distinguishes apns-push-type — alert, background, voip, complication, fileprovider, mdm. An incorrect type on iOS 13+ causes background notifications not to wake the app. We've seen projects where content-available: 1 was sent without apns-push-type: background — the app didn't receive silent push on some devices, and the team spent a month looking for an 'app bug'.

FCM on Android works through Google Play Services. For devices without GMS (Huawei, part of the Chinese market), Huawei Push Kit or a direct WebSocket is needed — a separate task. FCM supports data messages (handled in onMessageReceived) and notification messages (the system displays automatically if the app is in the background). Mixing them requires caution: if the notification block has a click_action but the deep link is not registered in the app, tapping the notification simply opens the main screen without navigation.

Why Segmentation Is the Foundation of Effective Push Notifications?

Sending to everyone indiscriminately quickly exhausts user loyalty. Personalized messages are clicked 3 times more often than bulk ones, and proper segmentation reduces churn by 25% (on one project it brought significant additional revenue per quarter). The cost of setting up segmentation in OneSignal or a custom backend depends on the complexity of filters.

Proper segmentation is built on several levels.

Topics are for broad categories: 'new promotions', 'order status updates'. User subscribes via FirebaseMessaging.getInstance().subscribeToTopic("orders"). Simple, but no flexible filtering.

Attribute-based segments — via OneSignal, Braze, or custom backend. We store in the user profile: language, device type, last activity, LTV segment. Notification goes only to those with last_active < 7_days and plan = premium. OneSignal allows building such filters in the interface without code.

Personalized — by specific device_token. It's important to store tokens correctly: the token updates on app reinstall, restoration from backup on a new phone, or resetting settings. On iOS, use UNUserNotificationCenter + didRegisterForRemoteNotificationsWithDeviceToken, save to backend on every launch, not just the first. Otherwise, after 3 months 30% of tokens in the database are outdated.

What Is Rich Push and How Does It Boost Conversion?

A standard notification with title and text is clicked less often than a rich push with image and action buttons — by 3 times. But implementing rich push is a separate task on each platform.

On iOS, rich content requires UNNotificationServiceExtension (to modify payload) and UNNotificationContentExtension (custom UI). The extension runs in a separate process with limited time and memory. If the extension crashes or exceeds the timeout, the system shows the original payload without media. A typical mistake is trying to load an image over HTTP (not HTTPS): ATS blocks the request, the extension silently fails, and the user sees a notification without an image.

On Android with API 26+, notifications are tied to NotificationChannel. If the channel is created with IMPORTANCE_LOW, sound and vibration are unavailable. Different notification types (transactional, marketing) should be in different channels so the user can disable marketing without losing order notifications. BigPictureStyle, MessagingStyle, InboxStyle are templates for expanded notifications. MessagingStyle with Person and avatars is the best choice for chats.

How to Track Delivery and Conversion of Push Notifications?

Sending a notification is half the work. It's important to know: was it delivered, opened, and did it lead to a target action.

FCM returns a MessageId on send, but does not guarantee a delivery callback — by design. For open tracking, custom logic is needed: on notification tap in onMessageReceived or via getInitialNotification() / onNotificationOpenedApp (OneSignal SDK), send an event to analytics with notification_id.

OneSignal provides built-in delivery and CTR analytics. For more detailed analysis — integrate with Amplitude or Mixpanel via webhook on open events. The budget for such a dashboard varies depending on event volume.

How We Implement Push Notifications: Typical Process

1. Audit current implementation — check token storage, update handling, notification types.
2. Design architecture — choose transport (FCM + APNs), segmentation layer (OneSignal/Braze/custom), personalization method.
3. Implementation — write registration code, inbound handling, rich push, deep linking.
4. Testing — send test campaigns, verify delivery on different devices, simulators, regions.
5. Monitoring and analytics — set up dashboard, open and conversion events.
6. Documentation and training — hand over operational materials to the team.

Typical stack: FCM + APNs at transport level, OneSignal or Firebase Notifications Composer for segmentation, custom backend for personalized event-based notifications. For large apps with >1M users, OneSignal has pricing limits — then we use Braze or a custom implementation on AWS SNS.

Timelines depend on complexity: basic FCM+APNs integration with transactional notifications — 1–2 weeks. A full system with segmentation, rich push, analytics, and A/B testing — 4–8 weeks. Order an audit of your current push infrastructure or get a consultation on implementing push notifications in your mobile app — we will contact you within a day and provide an accurate estimate.