Nepal Payment Go

A unified payment SDK for Nepal supporting multiple payment providers with a consistent API.

Features

• Unified API - Same interface for all providers
• Type-safe - Strongly typed requests and responses
• Production-ready - Proper error handling, timeouts, and logging
• Well-tested - Comprehensive test coverage
• Zero dependencies - Uses only Go standard library (except golang.org/x/crypto for ConnectIPS)

Supported Providers

Provider	Flow Type	Authentication	Status
eSewa	Form POST	HMAC-SHA256	✅ Ready
Khalti	Redirect	API Key	✅ Ready
ConnectIPS	Form POST	RSA-SHA256 Certificate	✅ Ready
FonePay	Redirect	HMAC-SHA512	✅ Ready

Installation

go get github.com/voidarchive/nepal-payment-go

Quick Start

eSewa (Wallet)

import "github.com/voidarchive/nepal-payment-go/providers/esewa"

provider, _ := esewa.New(esewa.Config{
    SecretKey:   "8gBm/:&EnhH.1/q",  // Sandbox key
    ProductCode: "EPAYTEST",
    Sandbox:     true,
})

// Initiate payment
resp, _ := provider.InitiatePayment(ctx, &core.PaymentRequest{
    Amount:      100,
    OrderID:     "ORDER-123",
    CallbackURL: "https://yoursite.com/callback",
})

// resp.IsFormPOST = true
// Generate HTML form with resp.FormFields, POST to resp.TargetURL

Khalti (Wallet)

import "github.com/voidarchive/nepal-payment-go/providers/khalti"

provider, _ := khalti.New(khalti.Config{
    SecretKey:  os.Getenv("KHALTI_SECRET_KEY"),
    WebsiteURL: "https://yoursite.com",
    Sandbox:    true,
})

resp, _ := provider.InitiatePayment(ctx, &core.PaymentRequest{
    Amount:      10000,  // In paisa (NPR 100)
    OrderID:     "ORDER-123",
    CallbackURL: "https://yoursite.com/callback",
})

// resp.IsFormPOST = false
// Redirect user to resp.TargetURL

ConnectIPS (Bank Transfer)

import "github.com/voidarchive/nepal-payment-go/providers/connectips"

provider, _ := connectips.New(connectips.Config{
    MerchantID:   os.Getenv("CONNECTIPS_MERCHANT_ID"),
    AppID:        os.Getenv("CONNECTIPS_APP_ID"),
    AppPassword:  os.Getenv("CONNECTIPS_APP_PASSWORD"),
    CertPath:     "/path/to/creditor.pfx",
    CertPassword: os.Getenv("CONNECTIPS_CERT_PASSWORD"),
    Sandbox:      true,
})

resp, _ := provider.InitiatePayment(ctx, &core.PaymentRequest{
    Amount:      100,
    OrderID:     "ORDER-123",
    CallbackURL: "https://yoursite.com/callback",
})

// resp.IsFormPOST = true
// Generate HTML form with resp.FormFields, POST to resp.TargetURL

FonePay (Bank/Wallet)

import "github.com/voidarchive/nepal-payment-go/providers/fonepay"

provider, _ := fonepay.New(fonepay.Config{
    MerchantCode: "NBQM",  // Sandbox
    SecretKey:    "a7e3512f5032480a83137793cb2021dc",
    Sandbox:      true,
})

resp, _ := provider.InitiatePayment(ctx, &core.PaymentRequest{
    Amount:      100,
    OrderID:     "ORDER-123",
    CallbackURL: "https://yoursite.com/callback",
})

// resp.IsFormPOST = false
// Redirect user to resp.TargetURL

FonePay Dynamic QR (In-Person Payments)

Generate QR codes for retail/in-person payments. Requires additional credentials from your bank.

provider, _ := fonepay.New(fonepay.Config{
    MerchantCode: "NBQM",
    SecretKey:    "a7e3512f5032480a83137793cb2021dc",
    Username:     os.Getenv("FONEPAY_USERNAME"),  // QR API credentials
    Password:     os.Getenv("FONEPAY_PASSWORD"),
    Sandbox:      true,
})

// Generate QR code
qr, _ := provider.GenerateQR(ctx, &fonepay.QRRequest{
    Amount:      500,
    OrderID:     "TABLE-42",
    Description: "Coffee Shop Order",
})

// Display QR to customer
// qr.QRImageData contains PNG bytes
// Save to file: os.WriteFile("payment.png", qr.QRImageData, 0644)

Payment Verification

All providers use the same verification pattern:

result, err := provider.VerifyPayment(ctx, &core.VerifyRequest{
    EncodedParams:  callbackParams,  // Query params from callback
    ExpectedAmount: 100,
})

if err != nil {
    if errors.Is(err, core.ErrAmountMismatch) {
        // Handle amount tampering
    }
    if errors.Is(err, core.ErrSignatureMismatch) {
        // Handle signature failure
    }
}

if result.Success {
    fmt.Printf("Payment complete! TxnID: %s", result.TransactionID)
}

Running the Demo

Combined Demo (All Providers)

go run ./examples/demo/

Open http://localhost:8080

Individual Provider Demos

go run ./examples/esewa/      # eSewa demo
go run ./examples/khalti/     # Khalti demo (needs KHALTI_SECRET_KEY)
go run ./examples/connectips/ # ConnectIPS demo (needs credentials)
go run ./examples/fonepay/    # FonePay demo

Sandbox Credentials

eSewa

Field	Value
Test ID	9806800001 - 9806800005
Password	Nepal@123
Token	123456
Secret Key	8gBm/:&EnhH.1/q
Product Code	EPAYTEST

Khalti

Field	Value
Test ID	9800000001 - 9800000005
MPIN	1111
OTP	987654
Secret Key	Get from Khalti Dashboard

ConnectIPS

Requires merchant onboarding with Nepal Clearing House (NCHL). You'll receive: Merchant ID, App ID, and .pfx certificate.

FonePay

Field	Sandbox Value
Merchant Code	NBQM
Secret Key	a7e3512f5032480a83137793cb2021dc

Note: FonePay sandbox may be unreliable. Contact FonePay for production credentials.

Environment Variables

# eSewa (optional - has sandbox defaults)
ESEWA_SECRET_KEY=8gBm/:&EnhH.1/q
ESEWA_PRODUCT_CODE=EPAYTEST

# Khalti (required)
KHALTI_SECRET_KEY=your_key_here

# ConnectIPS (required for ConnectIPS)
CONNECTIPS_MERCHANT_ID=your_merchant_id
CONNECTIPS_APP_ID=your_app_id
CONNECTIPS_APP_PASSWORD=your_password
CONNECTIPS_CERT_PATH=/path/to/creditor.pfx
CONNECTIPS_CERT_PASSWORD=cert_password

# FonePay (optional - has sandbox defaults)
FONEPAY_MERCHANT_CODE=NBQM
FONEPAY_SECRET_KEY=a7e3512f5032480a83137793cb2021dc

Project Structure

.
├── core/                    # Core contracts (dependency-free)
│   ├── models.go           # Request/Response types
│   ├── errors.go           # Sentinel errors & status constants
│   ├── provider.go         # Provider interface
│   └── mock.go             # Mock provider for testing
├── providers/
│   ├── esewa/              # eSewa implementation
│   ├── khalti/             # Khalti implementation
│   ├── connectips/         # ConnectIPS implementation
│   └── fonepay/            # FonePay implementation
└── examples/
    ├── demo/               # Combined demo (all providers)
    ├── esewa/              # eSewa standalone demo
    ├── khalti/             # Khalti standalone demo
    ├── connectips/         # ConnectIPS standalone demo
    └── fonepay/            # FonePay standalone demo

Core Types

// PaymentRequest initiates a payment
type PaymentRequest struct {
    Amount        int64   // Amount in smallest unit
    Currency      string  // Usually "NPR"
    OrderID       string  // Your unique order ID
    Description   string  // Payment description
    CallbackURL   string  // Where to redirect after payment
    CustomerEmail string  // Optional
    CustomerPhone string  // Optional
}

// PaymentResponse from InitiatePayment
type PaymentResponse struct {
    IsFormPOST    bool              // true = POST form, false = redirect
    TargetURL     string            // Where to send user
    FormFields    map[string]string // Form fields (if IsFormPOST)
    TransactionID string            // Provider's transaction ID
}

// VerifyResponse from VerifyPayment
type VerifyResponse struct {
    Success        bool
    TransactionID  string
    OrderID        string
    VerifiedAmount int64
    Currency       string
    Status         string  // StatusComplete, StatusPending, etc.
}

Error Handling

import "github.com/voidarchive/nepal-payment-go/core"

// Sentinel errors
core.ErrInvalidConfig    // Invalid provider configuration
core.ErrInvalidRequest   // Invalid payment request
core.ErrProviderError    // Provider returned an error
core.ErrAmountMismatch   // Verified amount doesn't match expected
core.ErrSignatureMismatch // Signature verification failed
core.ErrPaymentNotFound  // Transaction not found
core.ErrTimeout          // Request timed out
core.ErrRateLimited      // Rate limit exceeded

// Status constants
core.StatusComplete   // "complete"
core.StatusPending    // "pending"
core.StatusFailed     // "failed"
core.StatusCancelled  // "cancelled"
core.StatusExpired    // "expired"
core.StatusRefunded   // "refunded"

Testing

# Run all tests
go test ./... -v

# Run specific provider tests
go test ./providers/esewa/... -v
go test ./providers/khalti/... -v
go test ./providers/connectips/... -v
go test ./providers/fonepay/... -v

Security Notes

1. Never expose secret keys in client-side code
2. Always verify payments server-side before fulfilling orders
3. Validate amounts to prevent price manipulation
4. Use HTTPS in production for callback URLs
5. Store certificates securely (ConnectIPS .pfx files)

Contributing

Contributions are welcome! Feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details.