PhonePe App Using Jetpack Compose

🏦 How to Make a UPI App Like PhonePe Using Jetpack Compose

In today’s digital India, apps like PhonePe, Google Pay, and Paytm have revolutionized the way we handle money. These UPI-based payment apps enable lightning-fast transactions, 24x7 accessibility, and full bank-to-bank interoperability.

But have you ever wondered how to build your own UPI app just like PhonePe?

If you're an Android developer and want to learn how to build a UPI payment app using Jetpack Compose, this is your complete guide.

🚀 What is UPI and How Does It Work?

UPI (Unified Payments Interface) is a real-time payment system developed by the NPCI (National Payments Corporation of India). It allows users to link their bank accounts and send/receive money using:

• Mobile number
• Virtual Payment Address (like yourname@upi)
• QR code
• Bank account + IFSC

When you build a UPI app, you’re essentially creating a UI + backend layer over the UPI infrastructure provided by NPCI, with bank integrations.

🛠️ Tech Stack You’ll Need

Stack	Tools
Frontend	Jetpack Compose (Modern UI Toolkit)
Architecture	MVVM (Model-View-ViewModel)
Networking	Retrofit + Coroutines
Backend	UPI PSP Integration (with NPCI Certification)
Authentication	BiometricPrompt, OTP
Security	Device binding, PIN storage with Keystore
APIs	UPI Intents / Deep Linking / NPCI SDK
Database	Room or Firebase for transaction logs

🧩 How UPI Apps Actually Work

1. User links bank account through UPI-enabled bank via app.
2. App fetches bank details via PSP (Payment Service Provider).
3. User sets UPI PIN via the bank's issuer service.
4. Transactions are routed to NPCI, which communicates with the bank APIs.
5. The transaction status (SUCCESS / FAILURE / PENDING) is updated.

⚠️ You can't directly build a fully functional UPI backend unless you're a registered PSP with NPCI. But you can integrate UPI via intents or third-party aggregators.

🧱 Core Features to Build

1. User Onboarding and Mobile Verification

• OTP verification using Firebase or custom API
• Device binding (associate device ID with account)
• Permissions: SMS, Phone state, etc.

2. Bank Account Linking

• Show list of UPI-enabled banks
• Fetch accounts via UPI SDK or backend aggregator
• Save account with VPA (e.g., john@upi) locally

3. UPI PIN Setup

• Use UPI intent (upi://pay) to redirect to PSP or bank app
• Securely store status: Is UPI PIN set?

4. Send / Receive Money

Create payment UI using Compose:

TextField(value = amount, onValueChange = { ... })
Button(onClick = { initiateUPI() }) { Text("Pay Now") }
  

Use UPI deep linking for payment:

val uri = Uri.parse("upi://pay?pa=receiver@upi&pn=Receiver Name&mc=0000&tid=123456&tr=1234567890&tn=Payment&am=100&cu=INR")
val intent = Intent(Intent.ACTION_VIEW, uri)
startActivity(intent)
  

5. Transaction History

• Save each payment response (via Intent callback)
• Store to local Room DB
• Display in a scrollable list (Compose LazyColumn)

6. QR Code Scanner

• Use ML Kit or ZXing for QR code scanning
• On scan, parse UPI parameters from URI and proceed with payment

7. Notification and Alerts

• Show toast/Snackbar for transaction updates
• Push notifications (optional)

8. User Profile and Settings

• VPA management
• Linked bank account view
• App lock / biometric lock

🖼️ UI with Jetpack Compose (Example)

@Composable
fun PaymentScreen() {
    var amount by remember { mutableStateOf("") }

    Column(modifier = Modifier.padding(16.dp)) {
        Text("Enter Amount", fontSize = 20.sp)
        Spacer(modifier = Modifier.height(8.dp))
        OutlinedTextField(
            value = amount,
            onValueChange = { amount = it },
            label = { Text("Amount in ₹") },
            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number)
        )
        Spacer(modifier = Modifier.height(16.dp))
        Button(onClick = { initiatePayment(amount) }) {
            Text("Send Money")
        }
    }
}
  

🔐 Security Considerations

• Use BiometricPrompt for transaction confirmation
• Avoid saving sensitive data on device storage
• Always validate inputs before sending a UPI request
• Use Android Keystore for secure storage

🧪 Testing Your App

• Use UPI sandbox environments (e.g., Razorpay Sandbox)
• Test with test bank accounts (provided by NPCI)
• Handle all edge cases (timeout, network loss, etc.)

📱 Real-World UPI API Providers

• Razorpay
• Cashfree
• Paytm for Business
• PhonePe Switch (B2B SDK)

📋 Step-by-Step Development Plan

Step	Description
✅ 1	Setup Jetpack Compose + MVVM
✅ 2	Build user login and verification screen
✅ 3	Fetch bank list and simulate linking
✅ 4	Integrate UPI intent-based payment
✅ 5	Add transaction result screen
✅ 6	Add QR scan feature
✅ 7	Store and display transaction history
✅ 8	Secure the app with biometrics
✅ 9	Publish to Play Store with disclaimer

🤝 Legal & Compliance Notes

• You must be licensed by NPCI if you want to create your own PSP.
• Use only approved UPI SDKs or aggregators.
• Follow RBI’s data storage and encryption norms.

🎯 Final Thoughts

Creating a UPI app like PhonePe with Jetpack Compose is definitely possible—but a real-world version requires:

• Strong UI/UX
• Understanding of UPI workflows
• Legal compliance and security
• Integration with official SDKs or PSPs

💡 Pro Tip: Focus on creating a smooth and secure frontend with Jetpack Compose. Then explore integration options with UPI service providers or aggregators.

📚 Useful Resources

• NPCI Official Website
• Jetpack Compose Docs
• Razorpay UPI Integration
• NPCI UPI Documentation