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Building Hobfit: From Zero to Shark Tank with React Native

How I built a women's fitness app from scratch as the founding engineer, and watched it get pitched on national television.

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Building Hobfit: From Zero to Shark Tank with React Native

When I joined Hobfit as the founding engineer, it was just an idea. Six months later, I was watching the founders pitch it on Shark Tank India Season 5 — with the entire tech stack I built running live on national TV.

The Beginning

The founders had a clear vision: a women-centric fitness and wellness platform. No existing app truly understood the needs of women in India — from workout plans during menstrual cycles to nutrition that actually works for Indian diets.

I had one job: build it all.

The Tech Stack Decision

I chose React Native for a simple reason: we needed to ship on iOS and Android simultaneously with a tiny team (me). Here's what I picked:

  • React Native + Expo — Fast iteration, OTA updates, managed workflow
  • Express.js backend — Simple, scalable, perfect for rapid prototyping
  • Firestore — Real-time sync, offline support, scales automatically
  • Next.js for web — Marketing site + web app on Vercel
  • Razorpay — Indian payment gateway integration

No fancy microservices. No over-engineering. Just ship.

The Build

Month 1: Core Features

I started with the fundamentals:

// User onboarding flow
const OnboardingScreen = () => {
  const [goals, setGoals] = useState<FitnessGoal[]>([]);
  const [fitnessLevel, setFitnessLevel] = useState<FitnessLevel>();

  // Personalized workout plan generation
  const generatePlan = async () => {
    const plan = await createWorkoutPlan({
      goals,
      fitnessLevel,
      availableEquipment,
      timePerDay,
    });

    await saveToPlan(plan);
  };

  return (
    // UI implementation
  );
};

The onboarding had to be perfect. We needed:

  • Fitness goals selection
  • Current fitness level assessment
  • Equipment availability
  • Time commitment
  • Dietary preferences

All of this fed into personalized workout and meal plans.

Month 2: Workout Tracking

The workout tracker was the heart of the app:

  • Video demonstrations for each exercise
  • Rep/set tracking with voice feedback
  • Progress photos with before/after comparisons
  • Real-time form corrections (future ML feature)
// Workout session state management
const WorkoutSession = () => {
  const [currentExercise, setCurrentExercise] = useState(0);
  const [sets, setSets] = useState<Set[]>([]);
  const [isResting, setIsResting] = useState(false);

  const completeSet = (reps: number, weight?: number) => {
    const newSet = {
      reps,
      weight,
      timestamp: new Date(),
    };

    setSets([...sets, newSet]);

    // Auto-start rest timer
    if (currentExercise < workout.exercises.length - 1) {
      startRestTimer(workout.restTime);
    }
  };

  return (
    // Session UI
  );
};

Month 3: Community Features

Women wanted to connect with others on the same journey:

  • Community feed with progress posts
  • Private groups for accountability
  • Challenges and competitions
  • Expert Q&A

Firestore made the real-time feed trivial to implement.

Month 4-5: Polish & Payments

The last two months were all about:

  • Performance optimization (app launch time < 2s)
  • Razorpay subscription integration
  • Push notifications for workout reminders
  • App Store + Play Store submissions
  • Marketing website on Next.js

The Shark Tank Pitch

When the founders walked onto the Shark Tank stage, I was watching from my apartment. Every feature they demoed — the workout tracker, the meal plans, the community feed — I had built.

The app didn't crash. The payments worked. The real-time features synced perfectly.

That's the moment I realized I'm pretty good at this.

What I Learned

  1. Ship fast, iterate faster — Perfect is the enemy of done
  2. React Native is production-ready — Don't let anyone tell you otherwise
  3. Firestore is magic — For small teams, it's a superpower
  4. Users don't care about your tech stack — They care if it works
  5. One engineer can build a lot — With the right tools and focus

Tech Choices I'd Make Again

  • ✅ React Native + Expo
  • ✅ Firestore for real-time features
  • ✅ Next.js for marketing site
  • ✅ Vercel for deployment

Tech Choices I'd Reconsider

  • 🤔 Express.js → Maybe Next.js API routes for everything
  • 🤔 Manual video encoding → Use a service like Mux

The Metrics

After 6 months:

  • 10k+ downloads across iOS and Android
  • 2k+ active subscribers
  • 4.8/5 rating on Play Store
  • Featured on Shark Tank India Season 5

Not bad for a solo founding engineer.

Want to Build Something Like This?

The stack is simpler than you think:

npx create-expo-app my-fitness-app
npm install @react-navigation/native firebase
npm install @stripe/stripe-react-native

That's it. The rest is just solving problems one at a time.

Currently: Hobfit is live on App Store and Play Store. We're growing fast and the tech stack is holding up beautifully.

If you're building a mobile app and wondering if you should use React Native — the answer is yes. Ship it.

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