An un-official Flutter plugin for eSewa Payment Gateway. With this plugin, you can easily integrate eSewa Payment Gateway into your Flutter app and start accepting payments from your customers. Whether you're building an eCommerce app or any other type of app that requires payments, this plugin makes the integration process simple and straightforward.

Cover Image

What’s new (v2 form + signature)

Uses eSewa v2 form endpoint
HMAC-SHA256 signature generated in Dart (no inline HTML)
WebView posts application/x-www-form-urlencoded
Success returns only base64 data via EsewaPaymentResponse

Installation

Add the dependency in your app’s pubspec.yaml:

dependencies:
  esewa_flutter: latestVersion

This package depends on:

dependencies:
  flutter_inappwebview: ^6.1.5
  crypto: ^3.0.6

Run:

flutter pub get

iOS and Android setup

Ensure minimum Flutter 3 and a recent iOS/Android toolchain.
iOS: WKWebView is used via flutter_inappwebview.
Android: no extra setup beyond plugin requirements.

Quick start

import 'package:esewa_flutter/esewa_flutter.dart';

// Inside a widget tree
EsewaPayButton(
  paymentConfig: ESewaConfig.dev(
    amount: 100.0,
    successUrl: 'https://developer.esewa.com.np/success',
    failureUrl: 'https://developer.esewa.com.np/failure',
    secretKey: 'YOUR_SECRET_KEY',
    // productCode: 'EPAYTEST', // optional for dev (defaults to EPAYTEST)
  ),
  onSuccess: (resp) {
    // resp.data is base64 string
    print('Success base64: ${resp.data}');
  },
  onFailure: (message) {
    print('Failed: $message');
  },
),

Or imperatively:

final result = await Esewa.i.init(
  context: context,
  eSewaConfig: ESewaConfig.live(
    amount: 100.0,
    successUrl: 'https://your.domain/success',
    failureUrl: 'https://your.domain/failure',
    secretKey: 'YOUR_SECRET_KEY',
    productCode: 'YOUR_MERCHANT_CODE',
  ),
);

if (result.hasData) {
  print(result.data!.data); // base64
} else {
  print(result.error);
}

With EsewaPayButton, the integration of eSewa Payment Gateway becomes even easier, as the payment process can be initiated with just a single button press.

Properties

The EsewaPayButton widget has the following parameters:

width: The width of the button (default is double.infinity).
height: The height of the button (default is 40.0).
color: The background color of the button (default is the primary color of the app).
borderColor: The border color of the button (default is the primary color of the app).
onSuccess: The callback function that is called when the payment is successful.
onFailure: The callback function that is called when the payment fails.
paymentConfig: The eSewa payment configuration object that is required to initialize the payment screen.
radius: The border radius of the button (default is 4).
widget: An optional widget to be placed instead of the title text field. If the user wants to place a row with the eSewa icon or different widget.
title: The title of the button (default is "Pay with Esewa").
textStyle: The text style of the button title.

Configuration

Constructors align to environments and endpoints:

// Live
ESewaConfig.live({
  required double amount,
  double? taxAmount = 0,
  double? productServiceCharge = 0,
  double? productDeliveryCharge = 0,
  double? totalAmount, // optional; defaults to amount + tax + service + delivery
  String serverUrl = 'https://epay.esewa.com.np/api/epay/main/v2/form',
  required String productCode, // Merchant product code
  String? transactionUuid,     // Optional; auto-generated if not provided
  required String successUrl,  // Redirect URL on success
  required String failureUrl,  // Redirect URL on failure
  String signedFieldNames = 'total_amount,transaction_uuid,product_code',
  required String secretKey,   // HMAC-SHA256 secret key
})

// Dev/RC
ESewaConfig.dev({
  required double amount,
  double? taxAmount = 0,
  double? productServiceCharge = 0,
  double? productDeliveryCharge = 0,
  double? totalAmount,
  String serverUrl = 'https://rc-epay.esewa.com.np/api/epay/main/v2/form',
  String productCode = 'EPAYTEST',
  String? transactionUuid,
  required String successUrl,
  required String failureUrl,
  String signedFieldNames = 'total_amount,transaction_uuid,product_code',
  required String secretKey,
})

Field definitions

amount: base amount to charge
taxAmount: tax amount
productServiceCharge: service charge
productDeliveryCharge: delivery charge
totalAmount: if omitted, computed as amount + tax + service + delivery
serverUrl: v2 form endpoint for the target environment
productCode: eSewa merchant code (EPAYTEST in dev)
transactionUuid: unique id; auto-generated if null
successUrl, failureUrl: your redirect endpoints
signedFieldNames: fields included in signature (default aligns with v2 spec)
secretKey: HMAC secret key provided by eSewa

Return payload

On success redirect, the plugin expects a data query parameter with a base64 string and returns:

EsewaPaymentResponse(data: '<base64>')

On failure redirect, the plugin returns an error message if message exists, otherwise a generic failure message.

Verify response integrity (mandatory)

After successful payment, eSewa redirects to your successUrl with response parameters encoded in Base64 under data.

Example (decoded response body):

{
  "transaction_code": "000AWEO",
  "status": "COMPLETE",
  "total_amount": 1000.0,
  "transaction_uuid": "250610-162413",
  "product_code": "EPAYTEST",
  "signed_field_names": "transaction_code,status,total_amount,transaction_uuid,product_code,signed_field_names",
  "signature": "62GcfZTmVkzhtUeh+QJ1AqiJrjoWWGof3U+eTPTZ7fA="
}

Example (response body encoded in Base64):

eyJ0cmFuc2FjdGlvbl9jb2RlIjoiMDAwQVdFTyIsInN0YXR1cyI6IkNPTVBMRVRFIiwidG90YWxfYW1vdW50IjoiMTAwMC4wIiwi
dHJhbNhY3Rpb25fdXVpZCI6IjI1MDYxMC0xNjI0MTMiLCJwcm9kdWN0X2NvZGUiOiJFUEFZVEVTVCIsInNpZ25lZF9maWVsZF9uYW1
lc yI6InRyYW5zYWN0aW9uX2NvZGUsc3RhdHVzLHRvdGFsX2Ftb3VudCx0cmFuc2FjdGlvbl91dWlkLHByb2R1Y3RfY29kZSxzaWdu
ZWRfZmllbGRfbmFtZXMiLCJzaWduYXR1cmUiOiI2MkdjZlpUbVZremh0VWVoK1FKMUFxaUpyam9XV0dvZjNVK2VUUFRaN2ZBPSJ9

You must verify the integrity of the decoded JSON by recomputing the signature using the same HMAC-SHA256 method as the request and comparing it to the signature field in the response JSON.

How it works

Creates a POST form body with fields: amount, tax_amount, total_amount, product_service_charge, product_delivery_charge, transaction_uuid, product_code, success_url, failure_url, signed_field_names, signature.
Signature is generated as HMAC-SHA256 over: total_amount=<...>,transaction_uuid=<...>,product_code=<...> and base64-encoded.
Loads an InAppWebView and posts to the configured v2 endpoint.
Listens for navigation to your successUrl or failureUrl and completes accordingly.

Troubleshooting

Ensure your successUrl and failureUrl are reachable and match exactly in config.
If you see "Couldn't resolve the package 'crypto'", run flutter pub get in the plugin and your app.
If success occurs without data, the plugin returns failure by design. Ensure your backend redirects with the base64 data query param.

Transaction status check (enquiry)

If a transaction was initiated but you did not receive a redirect, you can query the status API.

Testing (RC):

https://rc.esewa.com.np/api/epay/transaction/status/?product_code=EPAYTEST&total_amount=100&transaction_uuid=123

Production:

https://epay.esewa.com.np/api/epay/transaction/status/?product_code=EPAYTEST&total_amount=100&transaction_uuid=123

Example response:

{
  "product_code": "EPAYTEST",
  "transaction_uuid": "123",
  "total_amount": 100.0,
  "status": "COMPLETE",
  "ref_id": "0001TS9"
}

Possible statuses include PENDING, COMPLETE, FULL_REFUND, PARTIAL_REFUND, AMBIGUOUS, NOT_FOUND, CANCELED, and service unavailable errors.

Dev Testing Information

If you want to test eSewa payment integration in development environment, you can use the following information:

SecretKey: SecretKey for every merchant partner will be provided from eSewa For UAT, SecretKey will be 8gBm/:&EnhH.1/q (Input should be text type.)
Algorithm used for signature generation is SHA-256
Test eSewa IDs: You can use any of the following test eSewa IDs for testing purposes:
- 9806800001
- 9806800002
- 9806800003
- 9806800004
- 9806800005
Password: Nepal@123
OTP: 123456

Run the example app

Navigate to the example folder cd example
Install the dependencies
- flutter pub get
Set up configuration ESewaConfig.live() or directly run with just ESewaConfig.dev() in dev mode
Start the example
- Terminal : flutter run

License

This plugin is released under the MIT License. See LICENSE for details.

Contributions

Contributions are welcome! To make this project better, Feel free to open an issue or submit a pull request on Github..

Contact

If you have any questions or suggestions, feel free to contact me on LinkedIn.

What’s new (v2 form + signature)

Installation

iOS and Android setup

Quick start

Properties

Configuration

Field definitions

Return payload

Verify response integrity (mandatory)

How it works

Troubleshooting

Transaction status check (enquiry)

Dev Testing Information

Run the example app

License

Contributions

Contact

Libraries

esewa_flutter package

eSewa Flutter

What’s new (v2 form + signature)

Installation

iOS and Android setup

Quick start

Properties

Configuration

Field definitions

Return payload

Verify response integrity (mandatory)

How it works

Troubleshooting

Transaction status check (enquiry)

Dev Testing Information

Run the example app

License

Contributions

Contact

Libraries

esewa_flutter package