API Documentation

🔑 Authentication

All API requests require your API key in the request header.

Request Header

X-API-Key: pn_live_your_api_key_here
Content-Type: application/json

POST Create Payment

Initiate a new UPI payment session and get a QR code URL and deep link.

POST https://api.paynexus.in/v1/payment/create

Request Parameters

Parameter	Type	Required	Description
amount	float	Required	Amount in INR (e.g., 999.00)
order_id	string	Required	Your unique order identifier
callback_url	string	Required	Webhook URL for payment events
redirect_url	string	Optional	Redirect after payment completion
customer_name	string	Optional	Customer's name
customer_email	string	Optional	Customer's email
description	string	Optional	Payment description / note

PHP Example

$ch = curl_init("https://api.paynexus.in/v1/payment/create");
curl_setopt_array($ch, [
  CURLOPT_POST           => true,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_HTTPHEADER     => [
    "X-API-Key: pn_live_your_key",
    "Content-Type: application/json"
  ],
  CURLOPT_POSTFIELDS => json_encode([
    "amount"       => 1499.00,
    "order_id"     => "ORD_" . time(),
    "callback_url" => "https://yoursite.com/webhook",
    "redirect_url" => "https://yoursite.com/success",
    "description"  => "Product Purchase"
  ])
]);
$response = json_decode(curl_exec($ch), true);
// $response["payment_url"] — redirect customer here

Success Response (200)

{
  "status": "success",
  "txn_ref": "TXN20250115ABC123",
  "payment_url": "https://pay.paynexus.in/TXN20250115ABC123",
  "qr_url": "https://api.paynexus.in/v1/qr/TXN20250115ABC123.png",
  "upi_deep_link": "upi://pay?pa=merchant@upi&pn=Merchant&am=1499&tn=Order",
  "expires_at": "2025-01-15T10:33:00Z"
}

GET Verify Payment

Verify payment status by transaction reference.

GET https://api.paynexus.in/v1/payment/verify/{txn_ref}

Response

{
  "status": "success",
  "txn_ref": "TXN20250115ABC123",
  "amount": 1499.00,
  "utr_number": "UTR123456789",
  "payer_upi": "customer@paytm",
  "payer_name": "Rahul Sharma",
  "paid_at": "2025-01-15T10:27:45Z"
}

POST Generate QR Code

Generate a UPI QR code image for a specific amount.

POST https://api.paynexus.in/v1/qr/generate

Parameter	Type	Required	Description
amount	float	Optional	Fixed amount (leave blank for dynamic)
note	string	Optional	Transaction note displayed to payer
size	integer	Optional	QR size in px (200–800, default 300)

⚠ Error Codes

HTTP Code	Error Code	Description
400	INVALID_PARAMS	Missing or invalid request parameters
401	UNAUTHORIZED	Invalid or missing API key
402	PLAN_LIMIT	Monthly transaction limit exceeded
404	NOT_FOUND	Transaction or resource not found
409	DUPLICATE_ORDER	Order ID already exists
422	UPI_NOT_SET	Merchant UPI ID not configured
500	SERVER_ERROR	Internal server error

🔔 Webhook Events

PayNexus sends POST requests to your webhook URL when payment events occur.

Event	Description
payment.success	Payment received and confirmed
payment.failed	Payment attempt failed
payment.pending	Payment initiated but not confirmed
payment.expired	Payment window expired (5 minutes)
link.paid	Payment link was successfully paid