Webhooks - FossaPay

What are Webhooks?

Webhooks are HTTP callbacks that FossaPay sends to your server when events occur in your account. They enable you to receive real-time notifications about payments, payouts, settlements, and other important events.

Webhooks eliminate the need for polling and ensure your application stays in sync with FossaPay in real-time.

Why Use Webhooks?

Real-time Updates

Get notified immediately when events occur

Reduce Polling

No need to constantly check for updates

Automated Workflows

Trigger actions automatically based on events

Better UX

Update your users instantly about transaction status

Webhook Events

Deposit Events

Event	Description	When it fires
`deposit.completed`	Deposit completed successfully	When a deposit is successfully processed

Withdrawal Events

Event	Description	When it fires
`withdrawal.completed`	Withdrawal completed successfully	When a withdrawal is successfully processed

Transfer Events

Event	Description	When it fires
`transfer.completed`	Transfer completed successfully	When a transfer is successfully processed
`transfer.failed`	Transfer failed	When a transfer fails to process

Wallet Events

Event	Description	When it fires
`wallet.balance.updated`	Wallet balance updated	When a wallet balance is updated

Setting Up Webhooks

Configure Webhook URL

Set your webhook endpoint in the dashboard or via API: Via Dashboard:

Go to Settings → Webhooks
Enter your webhook URL
Copy the webhook secret

Via API:

await fossapay.webhooks.configure({
  url: 'https://your-app.com/webhooks/fossapay',
  events: [
    'deposit.completed',
    'withdrawal.completed',
    'transfer.completed',
    'transfer.failed',
    'wallet.balance.updated'
  ],
  secret: 'your-webhook-secret' // Optional: for signature verification
});

Webhook URL Requirements

Your webhook endpoint must:

Use HTTPS (HTTP not allowed in production)
Respond within 30 seconds
Return a 2xx status code for successful receipt
Handle duplicate events gracefully

Webhook URLs must be publicly accessible. Use services like ngrok for local development.

Webhook Payload

All webhooks follow this structure:

{
  "event": "deposit.completed",
  "eventId": "evt_abc123xyz",
  "timestamp": "2024-01-15T10:30:45Z",
  "data": {
    "transactionId": "txn_001",
    "customerId": "cus_123",
    "sender": {
      "address": "0x123...",
      "chain": "Ethereum"
    },
    "recipient": {
      "address": "0x456...",
      "chain": "Ethereum"
    },
    "amount": 1000000,
    "currency": "USDT",
    "reference": "dep-20240115-001",
    "status": "completed",
    "transactionType": "deposit",
    "blockchain": "Ethereum",
    "transactionHash": "0x789...",
    "explorerLink": "https://etherscan.io/tx/0x789...",
    "timestamp": "2024-01-15T10:30:40Z"
  }
}

Implementing Webhook Handler

Basic Handler (Node.js/Express)

const express = require('express');
const crypto = require('crypto');
const app = express();

app.use(express.json());

app.post('/webhooks/fossapay', async (req, res) => {
  // 1. Verify webhook signature
  const signature = req.headers['x-fossapay-signature'];
  const secret = process.env.FOSSAPAY_WEBHOOK_SECRET;
  if (!verifySignature(req.body, signature, secret)) {
    return res.status(401).send('Invalid signature');
  }

  // 2. Respond quickly (within 30 seconds)
  res.status(200).send('Webhook received');

  // 3. Process webhook asynchronously
  processWebhook(req.body).catch(err => {
    console.error('Webhook processing failed:', err);
  });
});

async function processWebhook(payload) {
  const { event, data } = payload;

  switch (event) {
    case 'deposit.completed':
      await handleDepositCompleted(data);
      break;

    case 'withdrawal.completed':
      await handleWithdrawalCompleted(data);
      break;

    case 'transfer.completed':
      await handleTransferCompleted(data);
      break;

    case 'transfer.failed':
      await handleTransferFailed(data);
      break;

    case 'wallet.balance.updated':
      await handleWalletBalanceUpdated(data);
      break;

    default:
      console.log('Unhandled event:', event);
  }
}

async function handleDepositCompleted(data) {
  // Credit customer wallet
  await db.transactions.create({
    id: data.transactionId,
    customer_id: data.customerId,
    amount: data.amount,
    type: 'credit',
    status: 'completed'
  });

  await db.wallets.increment({
    customer_id: data.customerId,
    amount: data.amount
  });

  // Notify customer
  await sendNotification(data.customerId, {
    title: 'Deposit Received',
    message: `Your wallet has been credited with ${data.amount} ${data.currency}`
  });
}

function verifySignature(payload, signature, secret) {
  const hash = crypto
    .createHmac('sha256', secret)
    .update(JSON.stringify(payload))
    .digest('hex');

  return crypto.timingSafeEqual(
    Buffer.from(signature, 'hex'),
    Buffer.from(hash, 'hex')
  );
}

app.listen(3000);

Python/Flask Example

from flask import Flask, request, jsonify
import hashlib
import hmac
import json

app = Flask(__name__)

@app.route('/webhooks/fossapay', methods=['POST'])
def handle_webhook():
    # Verify signature
    signature = request.headers.get('x-fossapay-signature')
    secret = os.environ['FOSSAPAY_WEBHOOK_SECRET']
    if not verify_signature(request.data, signature, secret):
        return 'Invalid signature', 401

    # Respond quickly
    payload = request.json

    # Process asynchronously
    process_webhook.delay(payload)  # Using Celery

    return 'Webhook received', 200

def verify_signature(payload, signature, secret):
    hash = hmac.new(
        secret.encode(),
        payload,
        hashlib.sha256
    ).hexdigest()

    return hmac.compare_digest(hash, signature)

def process_webhook(payload):
    event = payload['event']
    data = payload['data']

    if event == 'deposit.completed':
        handle_deposit_completed(data)
    elif event == 'withdrawal.completed':
        handle_withdrawal_completed(data)
    elif event == 'transfer.completed':
        handle_transfer_completed(data)
    elif event == 'transfer.failed':
        handle_transfer_failed(data)
    elif event == 'wallet.balance.updated':
        handle_wallet_balance_updated(data)

Security

Signature Verification

FossaPay signs all webhooks with HMAC SHA256:

const crypto = require('crypto');

function verifyWebhookSignature(payload, signature, secret) {
  const hash = crypto
    .createHmac('sha256', secret)
    .update(JSON.stringify(payload))
    .digest('hex');

  return crypto.timingSafeEqual(
    Buffer.from(hash),
    Buffer.from(signature)
  );
}

Use IP whitelisting as an additional layer of security, not as a replacement for signature verification.

Retry Logic

If your endpoint doesn’t respond with a 2xx status, FossaPay retries:

Attempt	Delay
1st retry	5 minutes
2nd retry	30 minutes
3rd retry	2 hours
4th retry	6 hours
5th retry	24 hours

After 5 failed attempts, the webhook is marked as failed and no more retries occur.

Check your webhook logs in the dashboard for failed deliveries and investigate issues promptly.

Idempotency

Webhooks may be delivered more than once. Implement idempotent handling:

async function handleDepositCompleted(data) {
  const existingTransaction = await db.transactions.findOne({
    id: data.transactionId
  });

  if (existingTransaction) {
    console.log('Transaction already processed');
    return; // Skip duplicate
  }

  // Process deposit
  await db.transactions.create({
    id: data.transactionId,
    // ... other fields
  });
}

Testing Webhooks

Local Testing with ngrok

# Start ngrok
ngrok http 3000

# Use the HTTPS URL in FossaPay dashboard
# Example: https://abc123.ngrok.io/webhooks/fossapay

Simulate Webhooks

Test your webhook handler with simulated events:

curl -X POST https://api-production.fossapay.com/api/v1/webhooks/simulate \
  -H "Authorization: Bearer fp_test_sk_xxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "event": "deposit.completed",
    "customer_id": "cus_123",
    "amount": 1000000,
    "currency": "USDT"
  }'

Webhook Logs

View webhook delivery logs in your dashboard:

Go to Settings → Webhooks
Scroll down to “Webhook Events”
Filter by event type
Replay failed webhooks

Best Practices

Respond Quickly

Always return 200 immediately, then process asynchronously:

app.post('/webhooks', (req, res) => {
  res.status(200).send('OK');
  processAsync(req.body); // Don't await
});

Verify Signatures

Never trust webhooks without signature verification:

if (!verifySignature(payload, signature, secret)) {
  return res.status(401).send('Unauthorized');
}

Handle Duplicates

Use event_id or transaction_id to detect duplicates:

const processed = await redis.get(`webhook:${event_id}`);
if (processed) return;

await redis.set(`webhook:${event_id}`, '1', 'EX', 86400);

Log Everything

Log all webhook receipts for debugging and auditing:

logger.info('Webhook received', {
  event_id: payload.eventId,
  event: payload.event,
  timestamp: payload.timestamp
});

Monitor Failures

Set up alerts for webhook failures:

if (failureCount > threshold) {
  await sendAlert('Webhook failures detected');
}

Webhook Payload Examples

Deposit Completed (Crypto)

{
  "event": "deposit.completed",
  "eventId": "evt_abc123",
  "timestamp": "2024-01-15T10:30:45Z",
  "data": {
    "transactionId": "txn_001",
    "customerId": "cus_123",
    "sender": {
      "address": "0x123...",
      "chain": "Ethereum"
    },
    "recipient": {
      "address": "0x456...",
      "chain": "Ethereum"
    },
    "amount": 1000000,
    "currency": "USDT",
    "reference": "dep-20240115-001",
    "status": "completed",
    "transactionType": "deposit",
    "blockchain": "Ethereum",
    "transactionHash": "0x789...",
    "explorerLink": "https://etherscan.io/tx/0x789...",
    "timestamp": "2024-01-15T10:30:40Z"
  }
}

Deposit Completed (Fiat)

{
  "event": "deposit.completed",
  "eventId": "evt_def456",
  "timestamp": "2024-01-15T11:00:00Z",
  "data": {
    "transactionId": "txn_002",
    "customerId": "cus_456",
    "sender": {
      "accountName": "John Doe",
      "accountNumber": "0987654321",
      "bankName": "GTBank"
    },
    "recipient": {
      "accountName": "Jane Smith",
      "accountNumber": "0123456789",
      "bankName": "GTBank"
    },
    "amount": 50000,
    "currency": "NGN",
    "fee": 500,
    "reference": "dep-20240115-002",
    "status": "completed",
    "transactionType": "deposit",
    "notes": "Bank transfer deposit",
    "timestamp": "2024-01-15T11:00:00Z"
  }
}

Withdrawal Completed

{
  "event": "withdrawal.completed",
  "eventId": "evt_xyz789",
  "timestamp": "2024-01-15T11:45:23Z",
  "data": {
    "transactionId": "txn_003",
    "customerId": "cus_789",
    "recipient": {
      "accountName": "Jane Smith",
      "accountNumber": "0123456789",
      "bankName": "GTBank"
    },
    "amount": 25000,
    "currency": "NGN",
    "reference": "wth-20240115-001",
    "status": "completed",
    "transactionType": "withdrawal",
    "timestamp": "2024-01-15T11:45:20Z"
  }
}

Transfer Completed

{
  "event": "transfer.completed",
  "eventId": "evt_transfer1",
  "timestamp": "2024-01-15T12:30:00Z",
  "data": {
    "transactionId": "txn_004",
    "customerId": "cus_123",
    "sender": {
      "address": "0x123...",
      "chain": "Ethereum"
    },
    "recipient": {
      "address": "0x456...",
      "chain": "Ethereum"
    },
    "amount": 500000,
    "currency": "USDT",
    "reference": "trf-20240115-001",
    "status": "completed",
    "transactionType": "transfer",
    "blockchain": "Ethereum",
    "transactionHash": "0xabc...",
    "timestamp": "2024-01-15T12:30:00Z"
  }
}

Transfer Failed

{
  "event": "transfer.failed",
  "eventId": "evt_transfer2",
  "timestamp": "2024-01-15T13:15:00Z",
  "data": {
    "transactionId": "txn_005",
    "customerId": "cus_456",
    "sender": {
      "address": "0x789...",
      "chain": "Ethereum"
    },
    "recipient": {
      "address": "0xabc...",
      "chain": "Ethereum"
    },
    "amount": 300000,
    "currency": "USDT",
    "reference": "trf-20240115-002",
    "status": "failed",
    "transactionType": "transfer",
    "blockchain": "Ethereum",
    "transactionHash": "0xdef...",
    "timestamp": "2024-01-15T13:15:00Z"
  }
}

Wallet Balance Updated

{
  "event": "wallet.balance.updated",
  "eventId": "evt_balance1",
  "timestamp": "2024-01-15T14:00:00Z",
  "data": {
    "fromAccount": {
      "accountNumber": "0123456789",
      "accountName": "Main Wallet",
      "bankName": "GTBank"
    },
    "toAccount": {
      "accountNumber": "0987654321",
      "accountName": "Savings Wallet",
      "bankName": "GTBank"
    },
    "amount": 25000,
    "currency": "NGN",
    "reference": "bal-20240115-001",
    "type": "withdrawal/deposit",
    "customerId": "cus_123",
    "narration": "Transfer between accounts",
    "timestamp": "2024-01-15T14:00:00Z"
  }
}

Next Steps

Configure Webhooks

Set up your webhook endpoint

View Webhook Logs

Monitor webhook deliveries

Collections Guide

Handle payment webhooks

Payouts Guide

Handle payout webhooks

​What are Webhooks?

​Why Use Webhooks?

Real-time Updates

Reduce Polling

Automated Workflows

Better UX

​Webhook Events

​Deposit Events

​Withdrawal Events

​Transfer Events

​Wallet Events

​Setting Up Webhooks

​Configure Webhook URL

​Webhook URL Requirements

​Webhook Payload

​Implementing Webhook Handler

​Basic Handler (Node.js/Express)

​Python/Flask Example

​Security

​Signature Verification

​Retry Logic

​Idempotency

​Testing Webhooks

​Local Testing with ngrok

​Simulate Webhooks

​Webhook Logs

​Best Practices

​Webhook Payload Examples

​Deposit Completed (Crypto)

​Deposit Completed (Fiat)

​Withdrawal Completed

​Transfer Completed

​Transfer Failed

​Wallet Balance Updated

​Next Steps

Configure Webhooks

View Webhook Logs

Collections Guide

Payouts Guide

What are Webhooks?

Why Use Webhooks?

Webhook Events

Deposit Events

Withdrawal Events

Transfer Events

Wallet Events

Setting Up Webhooks

Configure Webhook URL

Webhook URL Requirements

Webhook Payload

Implementing Webhook Handler

Basic Handler (Node.js/Express)

Python/Flask Example

Security

Signature Verification

Retry Logic

Idempotency

Testing Webhooks

Local Testing with ngrok

Simulate Webhooks

Webhook Logs

Best Practices

Webhook Payload Examples

Deposit Completed (Crypto)

Deposit Completed (Fiat)

Withdrawal Completed

Transfer Completed

Transfer Failed

Wallet Balance Updated

Next Steps