This guide walks you through a complete payment integration using a Node.js backend as an example. The same concepts apply to any programming language.
Overview
1. Set Up Your Server
Install the required dependencies:
npm init -y
npm install express axios
// server.js
const express = require('express');
const crypto = require('crypto');
const axios = require('axios');
const app = express();
const KYREN_API_KEY = process.env.KYREN_API_KEY;
const KYREN_WEBHOOK_SECRET = process.env.KYREN_WEBHOOK_SECRET;
const KYREN_BASE_URL = 'https://api.kyren.top';
// Parse JSON for regular routes
app.use(express.json());
2. Create a Product (One-Time Setup)
You only need to create a product once. You can do this via the API or the Dashboard.
async function createProduct() {
const response = await axios.post(`${KYREN_BASE_URL}/v1/products`, {
name: '1000 AI Credits',
description: 'Top up 1000 credits for AI API usage',
price: 9.99,
currency: 'USD',
metadata: { credits: '1000' }
}, {
headers: { 'x-api-key': KYREN_API_KEY }
});
console.log('Product created:', response.data.data.id);
return response.data.data;
}
3. Create Checkout Endpoint
Add an endpoint that creates a checkout session when the customer clicks “Buy”:
app.post('/api/buy-credits', async (req, res) => {
try {
const response = await axios.post(`${KYREN_BASE_URL}/v1/checkouts`, {
productId: 'prod_abc123', // Your product ID from step 2
successUrl: 'https://yoursite.com/payment/success',
cancelUrl: 'https://yoursite.com/payment/cancel',
customerEmail: req.body.email,
metadata: {
userId: req.body.userId
}
}, {
headers: { 'x-api-key': KYREN_API_KEY }
});
// Return the checkout URL to the frontend
res.json({ checkoutUrl: response.data.data.url });
} catch (error) {
console.error('Checkout creation failed:', error.response?.data);
res.status(500).json({ error: 'Failed to create checkout' });
}
});
4. Handle the Frontend Redirect
On your frontend, redirect the customer to the checkout page:
<button id="buy-btn">Buy 1000 Credits - $9.99</button>
<script>
document.getElementById('buy-btn').addEventListener('click', async () => {
const response = await fetch('/api/buy-credits', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({
email: 'customer@example.com',
userId: 'user_123'
})
});
const { checkoutUrl } = await response.json();
window.location.href = checkoutUrl;
});
</script>
5. Handle Webhooks
Add a webhook endpoint to receive payment notifications:
function verifySignature(payload, signature, timestamp) {
const data = `${timestamp}.${payload}`;
const expected = 'sha256=' + crypto
.createHmac('sha256', KYREN_WEBHOOK_SECRET)
.update(data)
.digest('hex');
// Verify timestamp is within 5 minutes
const currentTime = Math.floor(Date.now() / 1000);
if (Math.abs(currentTime - parseInt(timestamp)) > 300) {
return false;
}
return crypto.timingSafeEqual(
Buffer.from(expected),
Buffer.from(signature)
);
}
app.post('/webhooks/kyren',
express.raw({ type: 'application/json' }),
(req, res) => {
const signature = req.headers['x-kyren-signature'];
const timestamp = req.headers['x-kyren-timestamp'];
const payload = req.body.toString();
if (!verifySignature(payload, signature, timestamp)) {
return res.status(400).send('Invalid signature');
}
const event = JSON.parse(payload);
switch (event.type) {
case 'order.paid':
const { order_id, product_id, customer_email, amount, currency } = event.data;
console.log(`Payment received: ${amount} ${currency} from ${customer_email}`);
// TODO: Fulfill the order — add credits to the user's account
break;
default:
console.log(`Unhandled event type: ${event.type}`);
}
res.status(200).send('OK');
}
);
6. Start the Server
app.listen(3000, () => {
console.log('Server running on http://localhost:3000');
});
KYREN_API_KEY=kyren_test_xxx KYREN_WEBHOOK_SECRET=whsec_xxx node server.js
7. Test the Flow
- Open your app and click “Buy 1000 Credits”
- You’ll be redirected to the Kyren Pay checkout page
- Enter test card number
4242 4242 4242 4242
- Complete the payment
- Check your server logs — you should see the webhook arrive
Congratulations! You’ve successfully integrated Kyren Pay. When you’re ready, switch to your live API key and start accepting real payments.
Next Steps
