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Nagad Online Payment API Integration Flutter Package

The nagad_payment_gateway package allows Flutter developers to integrate Nagad Online Payment into their applications. This package is ideal for merchants and service providers looking to enable digital payments using Nagad.

Credentials Provided by Nagad

Before integrating, obtain your credentials from Nagad:

final merchantID = "YOUR_MERCHANT_ID"
final merchantPrivateKey = "YOUR_MERCHANT_PRIVATE_KEY"
final pgPublicKey = "NAGAD_PAYMENT_GATEWAY_PUBLIC_KEY"

Initialize the Nagad instance:

Create an instance of Credentials and provide it to the Nagad Instance:

Nagad nagad = Nagad(
      credentials: const Credentials(
          merchantID: merchantID,
          merchantPrivateKey: merchantPrivateKey,
          pgPublicKey: merchantPrivateKey,
          isSandbox: true)); // Set to false for production

Note: Make sure to replace the provided credentials with your Nagad Sandbox or production credentials.

Additional Merchant Info

You can provide additional details about your service to be displayed on the payment page.

Merchant Info Fields

Field Name Max Length Description
serviceName 25 Service Name Provided by Merchant
serviceLogoURL 1~1024 Publicly accessible logo URL
additionalFieldName EN 20 Additional Field Name to be shown in Payment Page for Locale EN
additionalFieldName BN 20 Additional Field Name to be shown in Payment Page for Locale BN
additionalFieldValue 20 Value of Additional Field in English 
Map<String, dynamic> additionalMerchantInfo = {
        “serviceName” : “T Shirt”,
        “serviceLogoURL” : “tinyurl.com/sampleLogoUrl”,
        “additionalFieldNameEN” : “Color”,
        “additionalFieldNameBN” : “রং”,
        “additionalFieldValue” : “White”
    };

nagad.setAdditionalMerchantInfo(additionalMerchantInfo);

N.B: additionalMerchantInfo must be in Map<String, dynamic> type. Additional Merchant Info can be anything and will be saved for further usage. However only these fields will be shown in the payment page.

Initiate a Payment

To initiate a Regular Payment, use the pay method.

Payment Request

NagadResponse nagadResponse = await nagad.regularPayment(
  context,
  amount: 10.25,
  orderId: orderId,
);

Parameters

  • amount: The payment amount (Recommended as double).
  • orderId: A unique identifier for each payment. You can use milliseconds since epoch for uniqueness.

Example for Generating Unique Order ID

DateTime now = DateTime.now();
String orderId = 'order${now.millisecondsSinceEpoch}';

Payment Response Format

NagadResponse class contains:

  1. merchantId
  2. orderId
  3. paymentRefId
  4. amount
  5. clientMobileNo
  6. merchantMobileNo
  7. orderDateTime
  8. issuerPaymentDateTime
  9. issuerPaymentRefNo
  10. additionalMerchantInfo
  11. status
  12. statusCode
  13. cancelIssuerDateTime
  14. cancelIssuerRefNo
  15. serviceType

Note: Always store the required details in your database for future reference and reconciliation.

Testing in Sandbox Mode

To test payments in Sandbox Mode, ensure isSandbox: true is set when initializing Nagad. Use the test credentials provided by Nagad.

Production Deployment

When moving to production:

  • Change isSandbox: false.
  • Replace Sandbox credentials with production credentials.
  • Ensure your merchant account is verified by Nagad.

⚠️ Security Warning

Do not store merchant credentials directly in your Flutter application. Instead, use a secure backend server to handle payments securely and prevent exposure of sensitive data.

⚠️ Best Practices

✅ Use a backend server to securely process payments and store credentials.
✅ Never store or expose your merchantPrivateKey or other sensitive data in the frontend.

License

This package is licensed under the GNU General Public License (GPL) version 3.0.

© 2025 - Nagad Payment Gateway for Flutter

Links & References

Libraries

nagad_payment_gateway