Building Real-Time Event-Driven Applications with FluxRail: A Step-by-Step Guide

Introduction

Modern blockchain applications demand real-time reactivity. Whether you're tracking wallet deposits, monitoring smart contract events, or triggering automated workflows, waiting for manual polling is inefficient and costly. FluxRail's Core product provides a unified API for subscribing to blockchain events across 36+ chains, delivering signed webhooks instantly to your backend. In this guide, we'll build a real-time event-driven application from scratch using FluxRail – no SDKs, just raw HTTP calls.

Prerequisites

• A FluxRail account (sign up free)
• A test API key (flux_test_...)
• A webhook endpoint (e.g., https://your-app.com/webhook)
• Basic familiarity with curl or HTTP clients

Step 1: Create a Webhook Endpoint

FluxRail sends events to your endpoint via POST requests. First, register your webhook URL:

curl -X POST https://api.fluxrail.io/api/v1/webhooks \
  -H 'X-API-Key: flux_test_YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "url": "https://your-app.com/webhook",
    "description": "My production webhook",
    "events": ["transaction.confirmed", "token.transfer"]
  }'

The response includes a secret used to verify webhook signatures. Save it securely.

Step 2: Subscribe to an Address

Now subscribe to a blockchain address (e.g., a USDC wallet on Ethereum):

curl -X POST https://api.fluxrail.io/api/v1/subscriptions \
  -H 'X-API-Key: flux_test_YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "chain": "ethereum",
    "address": "0x1234567890abcdef1234567890abcdef12345678",
    "webhook_id": "wh_abc123",
    "confirmations": 2
  }'

FluxRail will start monitoring that address. When a transaction occurs, it sends a signed webhook to your endpoint.

Step 3: Verify Webhook Signatures

Every webhook includes an X-FluxRail-Signature header. Verify it using HMAC SHA-256 with your secret to ensure authenticity. Example in Node.js (Express):

const crypto = require('crypto');

app.post('/webhook', (req, res) => {
  const signature = req.headers['x-fluxrail-signature'];
  const payload = JSON.stringify(req.body);
  const expected = crypto
    .createHmac('sha256', process.env.FLUXRAIL_WEBHOOK_SECRET)
    .update(payload)
    .digest('hex');
  
  if (signature !== expected) {
    return res.status(401).send('Invalid signature');
  }
  // Process event
  console.log('Event received:', req.body);
  res.status(200).send('OK');
});

Step 4: Handle Events and Retries

FluxRail automatically retries failed deliveries up to 3 times. You can also manually retry from the dashboard or API:

curl -X POST https://api.fluxrail.io/api/v1/events/evt_xyz/retry \
  -H 'X-API-Key: flux_test_YOUR_API_KEY'

Check event logs for debugging:

curl https://api.fluxrail.io/api/v1/events?limit=10 \
  -H 'X-API-Key: flux_test_YOUR_API_KEY'

Step 5: Build an Event-Driven Workflow

Combine with FluxRail Pay for gas-free transfers. Example: when a deposit is detected, automatically initiate a payout:

// Inside webhook handler
if (event.type === 'transaction.confirmed' && event.data.token === 'USDC') {
  // Trigger a payout via FluxRail Payouts
  fetch('https://api.fluxrail.io/api/v1/payouts/customers/user-101/send', {
    method: 'POST',
    headers: {
      'X-API-Key': 'flux_live_YOUR_API_KEY',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      token: 'USDC',
      network: 'ERC20',
      amount: '100',
      dest_currency: 'USD',
      method: 'ach',
      destination: {
        account_owner_name: 'Jane Doe',
        account_number: '000123456789',
        routing_number: '110000000',
        account_type: 'checking'
      }
    })
  });
}

Conclusion

With FluxRail, building real-time event-driven applications becomes straightforward. You get a single API for monitoring, transfers, liquidity, and payouts – all with built-in compliance. Start with the free plan and scale as you grow. For more examples, visit our docs.