Build Your Android & iOS Mobile App in 2025: A Complete guide for beginner

Ready to build your first mobile app but want to use the web development skills you already have? 🤔 You've come to the right place! This guide is for beginners who want to turn a standard HTML, CSS, and JavaScript project into a native mobile app for both Android and iOS using Capacitor.

Let's dive in! 🚀

What is Hybrid Mobile App Development?

Imagine you write your code once using familiar web technologies (HTML, CSS, JavaScript) and it runs everywhere—on a website, on an iPhone, and on an Android phone. That’s the magic of hybrid mobile app development!

Traditional (Native) Way:

You write code in Swift/Objective-C for iPhones (iOS).
You write separate code in Kotlin/Java for Android phones.
That’s two different codebases, two different teams, and a lot more work. 😩

The Modern Hybrid Way (with Capacitor):

You write code once using HTML, CSS, and JavaScript.
Capacitor wraps your web app in a native "shell" and gives you access to native device features like the camera, GPS, and storage.
One codebase for all platforms! 🎉

Why Capacitor is Popular in 2025

Capacitor is a game-changer because it lets you take any web project and turn it into a native mobile app.

Bring Your Own Framework (or Don't!): You can use it with React, Angular, Vue, or even with plain HTML, CSS, and JS. You're not locked into any specific UI library.
Full Native Access: Capacitor provides a powerful bridge to access all native device features, from the camera to the filesystem.
Modern & Maintained: It's built by the team behind Ionic Framework and is the spiritual successor to Cordova/PhoneGap, with a focus on modern development practices.

For our UI, we'll use Bootstrap, a popular CSS framework, to make our app look good without writing tons of custom CSS.

Real-world examples of apps built with Capacitor:

Untappd: A popular social networking app for beer enthusiasts.
Sworkit: A leading fitness app with millions of users.
Amtrak: The official app for the US passenger railroad service.

Prerequisites for a Fresher (What You Need to Know)

You don't need to be an expert! But having a basic understanding of these will make your journey much smoother.

Basic Web Development:
- HTML: For structuring your app's content.
- CSS: For styling your app. A little knowledge of Bootstrap is a plus!
- JavaScript (ES6): The most important part! Understand variables, functions, and how to manipulate the DOM (e.g., document.getElementById).
Node.js Basics:
- You need Node.js and its package manager, npm, to install tools and manage project dependencies.
Git Basics:
- Knowing how to use Git for version control (clone, commit, push) is a must-have skill for any developer.

Pro Tip: Set up VS Code with these extensions for a great experience: Live Server, Prettier - Code formatter, ESLint.

🛠️ Development Environment Setup

Let's get your computer ready for action!

Install Node.js: Go to the official Node.js website and download the latest LTS (Long-Term Support) version. This will also install npm.
Install Android Studio (for Android):
- Download and install Android Studio.
- During setup, make sure you install the Android SDK and a virtual device (Emulator) to test your app.
Install Xcode (for iOS - Mac only):
- Open the App Store on your Mac and install Xcode.
- After installation, open Xcode to let it install its command-line tools.

📱 Creating Your First Capacitor App

Time for the fun part! Let's create a simple notes app.

Step 1: Create your project folder Create a new folder for your project and open it in VS Code.

mkdir my-notes-app
cd my-notes-app
npm init -y

This creates a package.json file for managing dependencies.

Step 2: Create your web app files Inside your folder, create two files: index.html and app.js.

index.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>My Notes App</title>
    <!-- Add Bootstrap for styling -->
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css" rel="stylesheet">
    <style>
        /* Simple style to make it feel more like an app */
        body { background-color: #f8f9fa; }
    </style>
</head>
<body>
    <div class="container py-4">
        <h1 class="mb-4">My Notes</h1>
        
        <div class="mb-3">
            <textarea id="note-input" class="form-control" rows="4" placeholder="Enter your note..."></textarea>
        </div>
        <button id="save-button" class="btn btn-primary w-100">Save Note</button>

        <h2 class="mt-5">Saved Notes</h2>
        <ul id="notes-list" class="list-group">
            <li class="list-group-item">No notes yet.</li>
        </ul>
    </div>

    <script src="app.js"></script>
</body>
</html>

app.js:

// We will add logic here later
console.log("App loaded!");

Step 3: Install Capacitor In your terminal, run the following commands to install Capacitor's CLI and core library.

npm install @capacitor/cli @capacitor/core

Step 4: Initialize Capacitor Now, let's turn this web project into a Capacitor project.

npx cap init

Capacitor will ask for your app name and a package ID. The defaults are usually fine. The important part is that it will create a capacitor.config.ts file.

Step 5: Add Native Platforms

# For Android
npx cap add android

# For iOS (Mac only)
npx cap add ios

This command creates an android or ios folder in your project.

📝 Building the Notes App Logic

Let's make our app functional by using Capacitor's Storage plugin.

Step 1: Install the Storage plugin This plugin lets us store data permanently on the device.

npm install @capacitor/storage

Step 2: Add logic to app.js Replace the content of app.js with this:

// Wait for the DOM to be ready
document.addEventListener('DOMContentLoaded', async () => {
    // Import from the global Capacitor object
    const { Storage } = Capacitor.Plugins;

    const noteInput = document.getElementById('note-input');
    const saveButton = document.getElementById('save-button');
    const notesList = document.getElementById('notes-list');

    // Function to load and display notes
    const loadNotes = async () => {
        const { keys } = await Storage.keys();
        notesList.innerHTML = ''; // Clear the list

        if (keys.length === 0) {
            notesList.innerHTML = '<li class="list-group-item">No notes yet.</li>';
            return;
        }

        for (const key of keys) {
            if (key.startsWith('note_')) {
                const { value } = await Storage.get({ key });
                const listItem = document.createElement('li');
                listItem.className = 'list-group-item';
                listItem.textContent = value;
                notesList.appendChild(listItem);
            }
        }
    };

    // Save a new note when the button is clicked
    saveButton.addEventListener('click', async () => {
        const noteText = noteInput.value.trim();
        if (noteText === '') return;

        const noteKey = `note_${Date.now()}`;
        await Storage.set({
            key: noteKey,
            value: noteText
        });

        noteInput.value = ''; // Clear the input
        await loadNotes(); // Reload the list
    });

    // Load initial notes when the app starts
    await loadNotes();
});

We use the Capacitor.Plugins global object because we are not using a module bundler. This is perfect for simple web projects.

🚀 Deploying the App to a Device

Now for the exciting part!

Sync Your Web Code: Every time you make a change to your HTML, CSS, or JS, you must run the sync command to copy it to the native projects.
```
npx cap sync
```
Open the Native Project:
```
# For Android
npx cap open android

# For iOS
npx cap open ios
```
This will launch Android Studio or Xcode.
Run the App:
- In Android Studio or Xcode, press the "Run" ▶️ button to deploy your app to an emulator or a connected physical device.

You should now see your web page running as a real native app! Try adding a note. It will be saved to the device's native storage.

Common Error & Fix:

Error: "API calls (e.g., fetch) not working on a real device."
Fix: For modern Android & iOS, you must serve your data over HTTPS. For development, you can add permissions to your native project to allow "cleartext" (non-HTTPS) traffic, but this is not recommended for production.

🎉 Conclusion

Congratulations! You've learned the fundamentals of hybrid app development and built a real, working mobile app with standard web technologies and Capacitor.

You now know how to: ✅ Create a web project and turn it into a native mobile app with Capacitor. ✅ Add native platforms (Android/iOS). ✅ Use Bootstrap for simple, clean styling. ✅ Access native features like Storage using Capacitor plugins. ✅ Build and deploy your app to a device.

Next Steps to Explore:

Frameworks: Try building this same app with a framework like React or Vue to manage your UI more efficiently.
Firebase: Add user authentication and a real-time database.
Push Notifications: Learn how to send notifications to your users using Capacitor's push notification plugin.
Advanced Plugins: Explore community plugins for features like payments, maps, and more!

Happy coding! You're now on your way to becoming a mobile app developer. 🚀

Ready to Innovate?

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Contact us via email, connect on WhatsApp at +91 9110245113, or book a free consultation to discuss your training or project needs.