Code Examples

Complete working examples for the most common operations. All examples use the hosted payment flow — the simplest integration path.

Base URL: https://4pay.online/api/v1

---

Python

Create a payment

import requests

API_KEY = "YOUR_API_KEY"
BASE_URL = "https://4pay.online/api/v1"

response = requests.post(
    f"{BASE_URL}/transactions",
    headers={
        "x-api-key": API_KEY,
        "Content-Type": "application/json",
    },
    json={
        "params": {
            "type": "payment",
            "amount": 1000,
            "currency": "USD",
            "txid": "order-12345",
            "returnUrl": "https://yoursite.com/success",
            "failUrl": "https://yoursite.com/fail",
            "notifyUrl": "https://yoursite.com/webhooks/payment",
        }
    },
)

tx = response.json()
print(f"Payment URL: {tx['payment_url']}")
# Redirect your user to tx['payment_url']

Check transaction status

tx_id = "550e8400-e29b-41d4-a716-446655440000"

response = requests.get(
    f"{BASE_URL}/transactions/{tx_id}",
    headers={"x-api-key": API_KEY},
)

tx = response.json()
print(f"Status: {tx['status']}")  # created, charged, failed, etc.

Create a payout

response = requests.post(
    f"{BASE_URL}/transactions",
    headers={
        "x-api-key": API_KEY,
        "Content-Type": "application/json",
    },
    json={
        "params": {
            "type": "payout",
            "amount": 5000,
            "currency": "RUB",
            "cardnumber": "4111111111111111",
            "txid": "payout-001",
        }
    },
)

tx = response.json()
print(f"Payout ID: {tx['id']}, Status: {tx['status']}")

Issue a refund

tx_id = "550e8400-e29b-41d4-a716-446655440000"

response = requests.put(
    f"{BASE_URL}/transactions/{tx_id}",
    headers={
        "x-api-key": API_KEY,
        "Content-Type": "application/json",
    },
    json={
        "params": {
            "type": "refund",
            "amount": 500,  # partial refund; omit for full refund
        }
    },
)

print(f"Refund status: {response.json()['status']}")

Webhook handler (Flask)

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route("/webhooks/payment", methods=["POST"])
def webhook():
    data = request.get_json()
    tx_id = data["id"]
    status = data["status"]

    if status == "charged":
        # Payment successful — fulfill the order
        print(f"Order {data['txid']} paid successfully")
    elif status == "failed":
        print(f"Order {data['txid']} failed: {data.get('error_description')}")

    return jsonify({"success": "true"})

if __name__ == "__main__":
    app.run(port=3000)

---

Node.js

Create a payment

const API_KEY = "YOUR_API_KEY";
const BASE_URL = "https://4pay.online/api/v1";

const response = await fetch(`${BASE_URL}/transactions`, {
  method: "POST",
  headers: {
    "x-api-key": API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    params: {
      type: "payment",
      amount: 1000,
      currency: "USD",
      txid: "order-12345",
      returnUrl: "https://yoursite.com/success",
      failUrl: "https://yoursite.com/fail",
      notifyUrl: "https://yoursite.com/webhooks/payment",
    },
  }),
});

const tx = await response.json();
console.log(`Payment URL: ${tx.payment_url}`);
// Redirect your user to tx.payment_url

Check transaction status

const txId = "550e8400-e29b-41d4-a716-446655440000";

const response = await fetch(`${BASE_URL}/transactions/${txId}`, {
  headers: { "x-api-key": API_KEY },
});

const tx = await response.json();
console.log(`Status: ${tx.status}`); // created, charged, failed, etc.

Create a payout

const response = await fetch(`${BASE_URL}/transactions`, {
  method: "POST",
  headers: {
    "x-api-key": API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    params: {
      type: "payout",
      amount: 5000,
      currency: "RUB",
      cardnumber: "4111111111111111",
      txid: "payout-001",
    },
  }),
});

const tx = await response.json();
console.log(`Payout ID: ${tx.id}, Status: ${tx.status}`);

Issue a refund

const txId = "550e8400-e29b-41d4-a716-446655440000";

const response = await fetch(`${BASE_URL}/transactions/${txId}`, {
  method: "PUT",
  headers: {
    "x-api-key": API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    params: {
      type: "refund",
      amount: 500, // partial refund; omit for full refund
    },
  }),
});

const tx = await response.json();
console.log(`Refund status: ${tx.status}`);

Webhook handler (Express)

import express from "express";
const app = express();
app.use(express.json());

app.post("/webhooks/payment", (req, res) => {
  const { id, txid, status, error_description } = req.body;

  if (status === "charged") {
    // Payment successful — fulfill the order
    console.log(`Order ${txid} paid successfully`);
  } else if (status === "failed") {
    console.log(`Order ${txid} failed: ${error_description}`);
  }

  res.json({ success: "true" });
});

app.listen(3000);

---

PHP

Create a payment

<?php
$apiKey = "YOUR_API_KEY";
$baseUrl = "https://4pay.online/api/v1";

$ch = curl_init("$baseUrl/transactions");
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        "x-api-key: $apiKey",
        "Content-Type: application/json",
    ],
    CURLOPT_POSTFIELDS => json_encode([
        "params" => [
            "type" => "payment",
            "amount" => 1000,
            "currency" => "USD",
            "txid" => "order-12345",
            "returnUrl" => "https://yoursite.com/success",
            "failUrl" => "https://yoursite.com/fail",
            "notifyUrl" => "https://yoursite.com/webhooks/payment",
        ],
    ]),
]);

$response = curl_exec($ch);
curl_close($ch);

$tx = json_decode($response, true);
echo "Payment URL: " . $tx["payment_url"] . "\n";
// Redirect your user to $tx["payment_url"]

Webhook handler

<?php
$payload = json_decode(file_get_contents("php://input"), true);

$txId = $payload["id"];
$status = $payload["status"];
$txid = $payload["txid"];

if ($status === "charged") {
    // Payment successful — fulfill the order
    error_log("Order $txid paid successfully");
} elseif ($status === "failed") {
    error_log("Order $txid failed: " . $payload["error_description"]);
}

header("Content-Type: application/json");
echo json_encode(["success" => "true"]);