Flutter UPI SDK

This cluster aims to document all the knowledge base for UPI transactions. Implementation of most of the UPI flows is different when compared to normal transactions.

There are broadly two types of UPI transactions, Collect and Intent(Pure Intent/In-App). For collect transactions, PayU informs the payment gateway to trigger a transaction to the app linked to the provided VPA, which asks the user for approval.

For intent transactions, we delegate the transaction process to an external app like BHIM, Google Pay, etc, which lets users transfer money to a VPA specified by us. After that, we use the PG (related to the specified VPA) for verification. PayU has a pre-configured VPA (distinct on the PG-Merchant level) on which the app makes the user pay the amount. To integrate UPI SDK with React Native, see Integrate UPI SDK with Flutter.

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Prerequisites for Google Pay:

To start transacting through Google Pay™, register your business on Google using the Google Onboarding form, In this registration process, you need to add the merchant VPAs created by PayU for you. In the case of multiple VPAs, all of them need to be registered with Google.

To enable Google Pay, contact your Point of Contact at Google. For any further queries or help with onboarding, send a mail to PayU Mobile Integration Team.

Compatibility

Android

Min SDK Version: 21
Compile SDK Version: 31+
Kotlin 1.6.10

iOS

iOS version: 11

SDK Integration

To integrate the Flutter UPI SDK, perform the following steps:

Step 1: Include the SDK in your App

The UPI SDK for Flutter is offered through Flutter pub.dev. To add the SDK plugin use the following dependency in your app:

//Add plugin in your app 
$ flutter pub add payu_upi_flutter

//Import UPI Plugin in your dart code
import 'package:payu_upi_flutter/payu_upi_flutter.dart';

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Note: If you are developing for iOS, Install the pod using the following command inside “ios” folder.
//Install payu dependencies in your ios project. 
$ pod install 

Step 2: Initialize Flutter SDK

Declare the PayUUpiFlutter instance and initialize the object.

class _MyAppState extends State<MyApp> implements PayUUPIProtocol {
    late PayUUpiFlutter payUUpiFlutter;

  @override
  void initState() {
    super.initState();
    payUUpiFlutter = PayUUpiFlutter(this);
  }
}

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Note: If you are developing for iOS, make sure your minimum deployment target is iOS 11.

Step 3. Implement the Callback protocol

Implement PayUPIProtocol to receive hash and transaction callback.

class _MyAppState extends State<MyApp> implements PayUUPIProtocol

Implement the following methods in your class to receive the callbacks.

@override
onPayUUPIMakePayment(Map response) {

  String eventType = response[PayUEventType.eventType];
  switch(eventType) { 
      case PayUEventType.onPaymentSuccess: { 
           String eventResponse = parsePayUResponse(response);
           //handle PayU response 
      } 
      break; 
      case PayUEventType.onPaymentFailure: { 
           String eventResponse = parsePayUResponse(response);
           //handle PayU response
      } 
      break; 

      case PayUEventType.onErrorReceived: { 
           String eventResponse = parsePayUResponse(response);
           //handle PayU response
      } 
      break; 
    
      case PayUEventType.onPaymentTerminate: 
      {  
           String eventResponse = parsePayUResponse(response);
           //handle PayU response
      } 
      break; 
    
      default: { 
           //handle unknown events
       } 
      break; 
  } 
}

@override
onPayUUPIValidateVPA(Map response) {
   String eventType = response[PayUEventType.eventType];
  switch(eventType) { 
      case PayUEventType.onValidateSuccess: { 
           String eventResponse = parsePayUResponse(response);
           //handle PayU response
      } 
      break; 
    
      case PayUEventType.onErrorReceived: { 
           String eventResponse = parsePayUResponse(response);
           //handle PayU response
      } 
      break; 
    
      default: { 
           //handle unknown events
       } 
      break; 
  } 
}

String parsePayUResponse(Map response){
  var eventResponse = response[PayUEventType.eventResponse];
  return eventResponse != null ? eventResponse.toString() : "";
}

Step 4: Setup Payment Hashes

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Warning: Always generate the hash at your backend to ensure security.

Hash is required to authenticate the request and to make sure MiTM has not happened while data was traveling over the network. You have to set the hash in the hash parameter during the creation of payment parameters. Use the following format to generate the hash:

sha512(key|txnid|amount|productinfo|firstname|email|udf1|udf2|udf3|udf4|udf5||||||SALT)

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TPV Hash
For TPV transactions, use the following format to generate the hash:
sha512(key|txnid|amount|productinfo|firstname|email|udf1|udf2|udf3|udf4|udf5||||||beneficiarydetail|SALT)
The beneficiarydetail parameter value will be at last or the last value to be appended.{"beneficiaryAccountNumber":<Account No>,"ifscCode":<IFSC>}

Here is a sample hash value for your reference:

smsplus|1695662774012|1|Info|Abc|[[email protected]](mailto:[email protected])|udf1|udf2|udf3|udf4|udf5|||||| {"beneficiaryAccountNumber":"1234567890","ifscCode":"IFSC0000024"}|1b1b0

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SI Hash
For SI Trasnaction, use the following format to generate the hash :-
SHA512(key|txnid|amount|productinfo|firstname|email|udf1|udf2|udf3|udf4|udf5||||||si_details|SALT)
Here is sample hash value for reference :-
3TnMpV|PayU_1752232075823|1|Info|Abc|[[email protected]](mailto:[email protected])|udf1|udf2|udf3|udf4|udf5||||||\{"paymentStartDate":"2025-07-28","paymentEndDate":"2028-08-28","billingAmount":"100.00","billingCurrency":"INR","billingCycle":"MONTHLY","billingInterval":1,"billingRule":"MAX"}|g0nGFe03

Step 5: Generate Payment Parameters

Set up the payment parameters for the SDK to initiate a transaction request. Use the following sample code for a quick integration:

var additionalParam = {
  PayUAdditionalParamKeys.udf1: <user defined value 1>,
  PayUAdditionalParamKeys.udf2: <user defined value 2>,
  PayUAdditionalParamKeys.udf3: <user defined value 3>,
  PayUAdditionalParamKeys.udf4: <user defined value 4>,
  PayUAdditionalParamKeys.udf5: <user defined value 5>,
};
var payUPaymentParams = {
  key: <Merchant Key>,
  amount: <Amount>,
  product_info: <Product Info>,
  first_name: <First Name>,
  email: <Email>,
  phone: <Phone>,
  ios_surl: <SURL>,
  ios_furl: <FURL>,
  android_surl: <SURL>,
  android_furl: <FURL>,
  environment: <String>, //0 => Production 1 => Test
  user_credentials: <unique user identifier>
  transaction_id:<Transaction ID>,
  additional_param: additionalParam,
	hash: <Pass Hash Value>,
  beneficiary_account_number: <Beneficiary Account Number>,
  beneficiary_ifsc: <ifsc code>,
  payment_mode:<String> // for Intent flow use "INTENT", for collect flow use "upi",
  disable_intent_seamless_failure:  <String>, // -1 | 0 ,
	// package_name parameter used for Android only
  package_name: <String>, //package name for the specific UPI intent (i.e. 				'net.one97.paytm') // 
	// intent_app parameter used for IOS only
  intent_app : <String>, //scheme name for the specific UPI intent (i.e. 'phonepe') // 
};

var si_params = {
    "is_free_trial": "0",
    "si": '1',
    "si_details": {
      "is_free_trial": "0",
      "billing_amount": '100.00', //Required
      "billing_currency": 'INR',
      "billing_cycle": //Required
      'MONTHLY', // YEARLY | MONTHLY | WEEKLY | DAILY | ONCE | ADHOC
      "billing_interval": 1, //Required
      "payment_start_date": '2025-07-28', //Required
      "payment_end_date": '2028-08-28', //Required
      "billing_limit": 'ON', //ON, BEFORE, AFTER
      "billing_rule": 'MAX', //MAX, EXACT
    }
  };

Payment Parameters

Parameter	Description	Notes
key `mandatory`	`String` This parameter must contain your merchant key received from PayU.	Cannot be null or empty
transaction_id `mandatory`	`String` It should be unique for each transaction.	Cannot be null or empty and should be unique for each transaction. The maximum allowed length is 25 characters. It cannot contain special characters like: -_/
amount `mandatory`	`String` Total transaction amount.	Cannot be null or empty and should be a valid double-stringified example: “100.0”
product_info `mandatory`	`String`Product information.	Cannot be null or empty
first_name `mandatory`	`String` Customer’s first name	Cannot be null or empty
email `mandatory`	`String` Customer’s email id	Cannot be null or empty
phone `mandatory`	`String` Customer’s phone number.	There should be a valid phone number
ios_surl `mandatory`	`String` When the transaction is successful, PayU will load this URL and pass the transaction response. Note*: This field is applicable for iOS integration	Should be a valid URL
ios_furl `mandatory`	`String` When the transaction fails, PayU will load this URL and pass the transaction response. No****te: This field is applicable for iOS integration	Should be a valid URL
android_surl `mandatory`	`String` When the transaction is successful, PayU will load this URL and pass the transaction response. Note*: This field is applicable for Android integration	Should be a valid URL
android_furl `mandatory`	`String` When the transaction fails, PayU will load this URL and pass the transaction response. When the transaction is a success, PayU will load this URL and pass the transaction response. Note*: This field is applicable for Android integration	Should be a valid URL
environment `mandatory`	`String` Environment of SDK	"0" for Production and "1" for Test
user_credentials `mandatory`	`String`User bank account number for TPV transaction.
beneficiary_ifsc `no`	`String` IFSC of bank account for TPV transaction.
beneficiary_account_number	Users bank account number for TPV transaction.

Step 6: Initiate the payment

Initialise and launch the SDK by calling the following code snippet:

payUUpiFlutter.makeUPIPayment(params: <PayU Payment Params>);

Step 7: VPA validation

Initialise and launch the Flutter UPI SDK by calling the following code snippet to validate the VPA

  validateVPA() async {
    // ignore: prefer_interpolation_to_compose_strings
    var vpaHash = HashService.calculateHash(PayUTestCredentials.merchantKey +
        '|' +
        "validateVPA" +
        '|' +
        PayUTestCredentials.vpa +
        '|' +
        PayUTestCredentials.merchantSalt);
    var params = PayUParams.createPayUPaymentParams(PayUPaymentModeKeys.upi);
    params[PayUPaymentParamKey.vpa] = PayUTestCredentials.vpa;
    params[PayUPaymentParamKey.hashes] = {
      PayUPaymentParamKey.validate_vpa: vpaHash
    };
    var data = await payUUpiFlutter.validateVPA(params: params);
    showAlertDialog(context, "Validate VPA", "$data");
  }

Response

The sample response of a VPA validation request is similar to the following:

{
  "status": "SUCCESS",
  "vpa": "9999999999@upi",
  "isVPAValid": 0,
  "payerAccountName": "PayUNeer",
  "isAutoPayVPAValid": 0,
  "isAutoPayBankValid": "NA"
}

Step 8: List the UPI apps

Initialise and launch the Flutter UPI SDK by calling the following code snippet to get the list of UPI apps installed on Android and iOS devices

  intentApps() async {
    var data = await payUUpiFlutter.intentApps();
    showAlertDialog(context, "intentApps", "$data");
  }

Response

Here is how a sample response of UPI list request looks like:

{
  "data": {
    "value": "net.one97.paytm",
    "title": "Paytm"
  }
}

For IOS, UPI Intent (Mandatory)

For fetch the Installed UPI apps, Kindly add the query schemes in theinfo.plist:

	<key>LSApplicationQueriesSchemes</key>
	<array>
		<string>phonepe</string>
		<string>tez</string>
    <string>gpay</string>
		<string>paytm</string>
		<string>bhim</string>
		<string>credpay</string>
	</array>

Test the Integration and Go-Live

Test the integration

After the integration is complete, you must test the integration before you go live and start collecting payment. You can start accepting actual payments from your customers once the test is successful.

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Callout
The UPI in-app and UPI intent flow is not available in the Test mode.

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Testing checklist
Things to remember while testing an integration:

To test the integration make sure that you are making a transaction call to the test endpoint.

Use your test key and salt for the transaction requests. See Genearate test key and salt.

Set the value of the environment parameters to 1.

You can make test payments using one of the payment methods configured at the Checkout.

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Watch Out!
You must only use the Test merchant Key and Test Salt to carry out a test transaction.

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Test cards only for Test environment
These test cards, UPI, and Wallet credentials must only be used in the sandbox environment. Using these test cards in production environment may cause validation error.

Test credentials for supported payment methods

Following are the payment methods supported in PayU Test mode.

Test VPA for UPI

You can use either of the following VPAs to test your UPI-related integration:

For Testing the UPI Collect flow, Please follow the below steps:-

Once you enter the VPA click on the verify button and proceed to pay.
In NPCI page timer will start, Don't "CLICK" on click text. Please wait on the NPCI page.
The below link opens in the browser Paste the transaction ID at the end of the URL then click on the success/failure simulator page. After that, your app will redirect to your app with the transaction response.

https://pgsim01.payu.in/UPI-test-transaction/confirm/<Txn_id>

For Android

You can add the below metadata under the application tag in the manifest file to test the UPI Collect flow on test env:-

🚧
Ensure to remove the code from the manifest file before going live.

<application>
<meta-data android:name="payu_debug_mode_enabled" android:value="true" /> // set the value to false for production environment
<meta-data android:name="payu_web_service_url" android:value="https://test.payu.in" /> //Comment in case of Production-->
<meta-data android:name="payu_post_url" android:value="https://test.payu.in"/> //Comment in case of Production-->
</appliction>

Test UPI Intent/InApp flow

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Callout
The UPI in-app and UPI intent flow is not available in the Test mode.

Go-live Checklist

Go-Live Checkist

Ensure these steps before you deploy the integration in a live environment.

Collect Live Payments

After testing the integration end-to-end, after you are sure that the integration is working as expected, you can switch to live mode to start accepting payments from your customers.

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Watch Out!
Ensure that you are using the production merchant key and salt generated in the live mode.

Checklist 2: Configure environment() parameter

Set the value of the environment()to 0 in the payment integration code. This enables the integration to accept live payments.

Checklist 4:- Remove/comment meta -data code from manifest file :-

For Android

You must be comment/remove the below metadata code from the manifest file to use the UPI Collect flow on Production env:-

<application>
<meta-data android:name="payu_debug_mode_enabled" android:value="true" /> // set the value to false for production environment
<meta-data android:name="payu_web_service_url" android:value="https://test.payu.in" /> //Comment in case of Production-->
<meta-data android:name="payu_post_url" android:value="https://test.payu.in"/> //Comment in case of Production-->
</appliction>

Checklist 5: Configure verify payment method

Configure the Verify payment method to fetch the payment status. We strongly recommend that you use this as a back up method to handle scenarios where the payment callback is failed due to technical error.

Checklist 6: Configure Webhook

We recommend that you configure Webhook to receive payment responses on your server. For more information, refer to Webhooks.

Sample app

The sample app for Flutter UPI SDK can be found in the following Github location:

https://github.com/payu-intrepos/PayU-UPI-Flutter.git

Updated 2 days ago

Compatibility

iOS

SDK Integration

TPV Hash

SI Hash

Test the Integration and Go-Live

Callout

Testing checklist

Watch Out!

Test cards only for Test environment

Ensure to remove the code from the manifest file before going live.

Callout

Go-Live Checkist

Watch Out!

For Android

Sample app

EXAMPLE QUESTIONS