Handling Webhooks

Webhooks are HTTP callbacks that notify your application when events occur in Zentra. Use them to update your database, trigger workflows, and keep your app in sync.

What You’ll Learn

Set up webhook endpoints
Verify webhook signatures
Handle different event types
Build reliable webhook processing
Debug common issues

Prerequisites

A publicly accessible server (or ngrok for local development)
Webhook endpoint URL configured in the Developer Console

Webhook Flow

┌──────────────┐     ┌──────────────┐     ┌──────────────┐
│  Zentra API  │────▶│  Your Server │────▶│  Your Logic  │
│   (Event)    │     │  (Webhook)   │     │  (Process)   │
└──────────────┘     └──────────────┘     └──────────────┘
       │                    │                    │
       │   1. Event         │                    │
       │      Occurs        │                    │
       │                    │                    │
       │   2. POST to       │                    │
       │      your URL      │                    │
       │   ──────────────▶  │                    │
       │                    │   3. Verify        │
       │                    │      Signature     │
       │                    │   4. Process       │
       │                    │      Event         │
       │   ◀──────────────  │                    │
       │   5. Return 200    │                    │

Step 1: Create Your Webhook Endpoint

Set up an endpoint to receive webhook events:

const express = require('express');
const Zentra = require('@zentra/sdk');

const router = express.Router();
const client = new Zentra.Client({
  apiKey: process.env.ZENTRA_SECRET_KEY
});

// Use raw body for signature verification
router.post('/zentra', 
  express.raw({ type: 'application/json' }),
  async (req, res) => {
    const signature = req.headers['x-zentra-signature'];
    const payload = req.body.toString();
    
    // Verify signature
    const isValid = client.webhooks.verify(payload, signature);
    
    if (!isValid) {
      console.error('Invalid webhook signature');
      return res.status(401).send('Invalid signature');
    }
    
    const event = JSON.parse(payload);
    
    // Process the event
    try {
      await processWebhookEvent(event);
      res.status(200).send('OK');
    } catch (error) {
      console.error('Webhook processing failed:', error);
      res.status(500).send('Processing failed');
    }
  }
);

module.exports = router;

Always verify webhook signatures. Without verification, attackers could send fake events to your endpoint.

Step 2: Handle Event Types

Process different events based on their type:

async function processWebhookEvent(event) {
  const { type, data, timestamp } = event;
  
  // Check for duplicate events (idempotency)
  const exists = await db.webhookEvents.findUnique({
    where: { event_id: event.id }
  });
  
  if (exists) {
    console.log('Duplicate event, skipping:', event.id);
    return;
  }
  
  // Log the event
  await db.webhookEvents.create({
    data: {
      event_id: event.id,
      type,
      data: JSON.stringify(data),
      processed_at: new Date()
    }
  });
  
  // Route to appropriate handler
  switch (type) {
    // Payment events
    case 'payment.success':
      await handlePaymentSuccess(data);
      break;
    case 'payment.failed':
      await handlePaymentFailed(data);
      break;
    case 'payment.refunded':
      await handlePaymentRefunded(data);
      break;
      
    // Transfer events
    case 'transfer.completed':
      await handleTransferCompleted(data);
      break;
    case 'transfer.failed':
      await handleTransferFailed(data);
      break;
      
    // Virtual account events
    case 'virtual_account.credited':
      await handleAccountCredited(data);
      break;
      
    // Card events
    case 'card.created':
      await handleCardCreated(data);
      break;
    case 'card.transaction':
      await handleCardTransaction(data);
      break;
      
    // Identity events
    case 'identity.verified':
      await handleIdentityVerified(data);
      break;
    case 'identity.failed':
      await handleIdentityFailed(data);
      break;
      
    default:
      console.log('Unhandled event type:', type);
  }
}

Step 3: Implement Event Handlers

Payment Success

async function handlePaymentSuccess(data) {
  const { reference, amount_minor, customer_email, metadata } = data;
  
  // Update order status
  const order = await db.orders.update({
    where: { reference },
    data: { 
      status: 'paid',
      paid_at: new Date(),
      amount_paid_minor: amount_minor
    }
  });
  
  // Trigger fulfillment
  await fulfillmentService.process(order.id);
  
  // Send receipt
  await emailService.send(customer_email, 'payment_receipt', {
    order_id: order.id,
    amount_major: amount_minor / 100
  });
}

Virtual Account Credited

async function handleAccountCredited(data) {
  const { account_id, amount_minor, sender_name, reference } = data;
  
  // Find user by virtual account
  const account = await db.virtualAccounts.findUnique({
    where: { zentra_id: account_id },
    include: { user: true }
  });
  
  if (!account) {
    console.error('Unknown account:', account_id);
    return;
  }
  
  // Credit user's wallet
  await db.wallets.update({
    where: { user_id: account.user_id },
    data: { 
      balance_minor: { increment: amount_minor }
    }
  });
  
  // Create transaction record
  await db.transactions.create({
    data: {
      user_id: account.user_id,
      type: 'deposit',
      amount_minor,
      description: `Deposit from ${sender_name}`,
      reference,
      status: 'completed'
    }
  });
  
  // Send push notification
  await pushService.send(account.user_id, {
    title: 'Money Received',
    body: `₦${(amount_minor / 100).toLocaleString()} from ${sender_name}`
  });
}

Transfer Completed

async function handleTransferCompleted(data) {
  const { reference, amount_minor, recipient_name } = data;
  
  await db.transfers.update({
    where: { reference },
    data: { 
      status: 'completed',
      completed_at: new Date()
    }
  });
  
  // Notify user
  const transfer = await db.transfers.findUnique({
    where: { reference },
    include: { user: true }
  });
  
  await pushService.send(transfer.user_id, {
    title: 'Transfer Successful',
    body: `₦${(amount_minor / 100).toLocaleString()} sent to ${recipient_name}`
  });
}

Webhook Events Reference

Payment Events

Event	Description
`payment.success`	Payment completed successfully
`payment.failed`	Payment failed
`payment.pending`	Payment is processing
`payment.refunded`	Payment was refunded

Transfer Events

Event	Description
`transfer.completed`	Transfer delivered
`transfer.failed`	Transfer failed
`transfer.pending`	Transfer is processing
`transfer.reversed`	Transfer was reversed

Virtual Account Events

Event	Description
`virtual_account.credited`	Money received
`virtual_account.created`	Account created
`virtual_account.closed`	Account closed

Card Events

Event	Description
`card.created`	Card issued
`card.transaction`	Card was used
`card.locked`	Card locked
`card.unlocked`	Card unlocked

Identity Events

Event	Description
`identity.verified`	KYC passed
`identity.failed`	KYC failed
`identity.pending`	KYC in review

Best Practices

1. Respond Quickly

Return a 200 status immediately, then process asynchronously:

router.post('/zentra', async (req, res) => {
  // Acknowledge receipt immediately
  res.status(200).send('OK');
  
  // Process in background
  processWebhookAsync(req.body).catch(console.error);
});

2. Handle Retries

Zentra retries failed webhooks with exponential backoff:

1st retry: 5 minutes
2nd retry: 30 minutes
3rd retry: 2 hours
4th retry: 8 hours
5th retry: 24 hours

After 5 failed attempts, the webhook is marked as failed. You can manually retry from the dashboard.

3. Store Raw Events

Save raw webhook data for debugging:

await db.webhookLogs.create({
  data: {
    event_id: event.id,
    type: event.type,
    raw_payload: JSON.stringify(event),
    received_at: new Date()
  }
});

4. Use Idempotency

Always check if you’ve already processed an event:

const processed = await db.webhookEvents.findUnique({
  where: { event_id: event.id }
});

if (processed) {
  return; // Already handled
}

Testing Webhooks

Local Development with ngrok

# Install ngrok
npm install -g ngrok

# Expose your local server
ngrok http 3000

# Use the ngrok URL in your webhook settings
# https://abc123.ngrok.com/webhooks/zentra

Trigger Test Events

Use the dashboard or CLI to send test webhooks:

zentra webhooks trigger payment.success --data '{
  "reference": "TEST_123",
  "amount_minor": 500000,
  "email": "test@example.com"
}'

Next Steps

Webhook API

API reference

Event Types

All event types

Verify Signatures

Signature verification

Going Live

Production checklist

Guides

​Handling Webhooks

​What You’ll Learn

​Prerequisites

​Webhook Flow

​Step 1: Create Your Webhook Endpoint

​Step 2: Handle Event Types

​Step 3: Implement Event Handlers

​Payment Success

​Virtual Account Credited

​Transfer Completed

​Webhook Events Reference

​Payment Events

​Transfer Events

​Virtual Account Events

​Card Events

​Identity Events

​Best Practices

​1. Respond Quickly

​2. Handle Retries

​3. Store Raw Events

​4. Use Idempotency

​Testing Webhooks

​Local Development with ngrok

​Trigger Test Events

​Next Steps

Webhook API

Event Types

Verify Signatures

Going Live

Handling Webhooks

What You’ll Learn

Prerequisites

Webhook Flow

Step 1: Create Your Webhook Endpoint

Step 2: Handle Event Types

Step 3: Implement Event Handlers

Payment Success

Virtual Account Credited

Transfer Completed

Webhook Events Reference

Payment Events

Transfer Events

Virtual Account Events

Card Events

Identity Events

Best Practices

1. Respond Quickly

2. Handle Retries

3. Store Raw Events

4. Use Idempotency

Testing Webhooks

Local Development with ngrok

Trigger Test Events

Next Steps