Building a Calorie Tracking App with Flutter + Firebase 📱🥗

I recently worked on a Calorie Counter & Tracker app designed to make daily nutrition and fitness tracking simple, fast, and practical.

The goal wasn't just to build another calorie calculator.

The focus was to create a complete tracking experience where users can scan food, log meals, monitor calories and nutrition, track exercise, record water intake, and stay consistent with their daily goals.

🔗 Live on Google Play: https://play.google.com/store/apps/details?id=com.app.calories.counter.appcrown.kkapptech

🛠️ Tech Stack

Frontend • Flutter • Dart • Responsive UI • Custom reusable widgets • State management

Backend & Cloud • Firebase Authentication • Cloud Firestore • Firebase Storage • Firebase Cloud Messaging • Firebase Analytics • Firebase Crashlytics

APIs & Integrations • Nutrition & calorie APIs • Food database integrations • Barcode scanning • Image recognition / AI-based food analysis • Exercise & activity data

🔍 Key Features I Built

📸 AI Food Scanning

One of the most interesting parts was making food logging faster through image recognition.

Instead of manually searching for every food item, users can capture an image of their meal and get estimated calorie and nutrition information.

The challenge here was designing the flow so that image analysis, API responses, loading states, errors, and user confirmation all worked smoothly together.

📊 Calorie & Nutrition Tracking

The app tracks daily food consumption and provides users with a clear overview of their calorie intake.

I worked on the underlying flow for:

→ Adding food → Managing meals → Calculating daily intake → Tracking nutrition values → Comparing intake against goals → Displaying progress clearly

🔎 Food Search

For cases where scanning isn't suitable, users can search for food and add it manually.

This required handling API-driven food data while keeping the experience fast and simple.

📦 Barcode Food Scanner

Packaged food can be added using barcode scanning, allowing users to quickly retrieve available nutrition information instead of entering everything manually.

🏃 Exercise Tracking

Food intake is only one side of the equation.

The app also allows users to log workouts and activities and view estimated calories burned based on the activity and duration.

💧 Water Tracking

I also implemented the daily water tracking flow so users can keep their hydration alongside their nutrition and exercise data.

🎯 Goals & Progress

Users can set calorie and activity goals and monitor their progress over time.

The challenge was keeping the dashboard informative without overwhelming the user with too much information.

🔥 Why Flutter + Firebase?

For this type of product, Flutter was a strong choice because it allowed us to build a consistent experience across Android and iOS while keeping the UI highly customizable.

Firebase handled much of the cloud infrastructure:

• Authentication • Real-time/cloud data • User-specific tracking data • File storage • Push notifications • Analytics • Crash monitoring

This allowed us to focus more of the development effort on the actual product experience and integrations instead of maintaining a large custom backend infrastructure.

⚙️ Some of the Engineering Challenges

Building a health & fitness tracking app isn't simply about creating screens.

Some of the important engineering work involved:

→ Designing scalable Firestore data structures → Connecting multiple third-party APIs → Handling asynchronous API responses → Managing image uploads and processing → Handling barcode scanning → Keeping calorie calculations consistent → Managing loading, empty and error states → Building reusable Flutter components → Implementing notifications and reminders → Monitoring crashes and production issues → Optimizing the app for a smooth mobile experience

📱 The Result

The final product brings multiple tracking workflows into a single mobile experience:

Food → Calories → Nutrition → Exercise → Water → Goals → Progress

The app is currently available on Google Play with features including food image recognition, barcode scanning, calorie tracking, exercise tracking, water tracking, and goal management.

For me, this project was a great example of how Flutter + Firebase + third-party APIs + AI-powered functionality can be combined to build a production-ready mobile product.

If you're building a health, fitness, nutrition, or AI-powered mobile app, I'd be happy to discuss how we can turn the idea into a working product.

So good! 👏

Wellcue – Comprehensive Health Tracking Mobile App

Wellcue is a production, cross-platform mobile app (iOS and Android) that helps people build and sustain healthy habits by tracking all of their health and wellness data in one place. It's built with Flutter on the frontend and powered by Supabase for the backend — PostgreSQL, authentication, storage, and Edge Functions — and is fully localized in English and Spanish.

Users log and monitor a wide range of health categories: blood pressure readings, exercise activities and duration, nutrition and hydration intake, medication schedules, sleep patterns, and body measurements. Each category supports detailed, timestamped entries and clear progress views, so people can see trends over time and stay consistent.

At the heart of the app is a robust reminder and notification engine. Users create fully customizable reminders with flexible recurring schedules (daily, specific days, or custom intervals) and receive reliable push notifications to keep their routines on track. The system is engineered to handle the real-world edge cases most apps miss: exact-time delivery, timezone-safe scheduling of the next occurrence, deduplication across devices, per-occurrence tracking, and automatic "missed reminder" follow-ups when a scheduled action goes unaddressed. Time-sensitive medication reminders are treated as critical health notifications on iOS.

Engineering highlights:

Reliable scheduled push notifications via a Supabase Edge Function + cron backend (Pushy / FCM), with retry, deduplication, and delivery verification

Strict per-user session isolation, guaranteeing that no data leaks across accounts on shared devices

Subscription and free-trial system integrated with RevenueCat and synced through a server-side webhook

Privacy-first monetization: GDPR/UMP consent flow and non-personalized ads (Google AdMob)

Riverpod state management on a Clean Architecture foundation, with resilient background sync

Full internationalization (EN/ES), including Unicode-safe validation for Latin American input

Wellcue is live and actively maintained on the App Store and Google Play, and meets Apple's and Google's health, privacy, and advertising review requirements.

Flutter with Supabase Edge Functions is a solid pairing here. The part I'd stress-test is a reading logged with no signal, since health data is what users assume is safe the second they hit save. Vitals and medication schedules also tend to want different conflict rules, because...