I'm building a payments integration and need to forward events to multiple downstream systems

A good pattern for this is an event fan-out / webhook router between your payments platform and downstream systems.

Recommended architecture

1. Payments system emits events

   • e.g. payment.succeeded, payment.failed, refund.created
   • Include a stable event_id, event_type, created_at, and payload

2. Event router / delivery service receives events

   • Validates authenticity
   • Normalizes the payload
   • Stores the event durably before delivery

3. Route to multiple downstream targets

   • Internal services
   • Partner webhooks
   • Message bus topics/queues
   • Analytics / data warehouse

4. Delivery worker pushes events asynchronously

   • Retry with exponential backoff
   • Dead-letter failed deliveries
   • Track per-destination status

Key design considerations

Reliability

• Use at-least-once delivery
• Make downstream consumers idempotent
• Persist events before forwarding

Ordering

• If ordering matters, preserve it per payment or per account
• Don’t assume global ordering across all events

Fan-out strategy

You can either:

• Broadcast all events to all systems, letting consumers filter, or
• Use routing rules so only relevant systems receive each event

Routing rules are usually better for payments because they reduce noise and risk.

Security

• Sign outbound requests
• Support mTLS or HMAC verification
• Encrypt sensitive fields
• Avoid sending raw PCI-sensitive data unless absolutely necessary

Observability

Track:

• Event received count
• Delivery success/failure per destination
• Retry counts
• Lag/latency
• Dead-letter queue size

Common implementation options

Option 1: Webhook dispatcher

Best if downstream systems are external or loosely coupled.

• Each destination has its own endpoint and secret
• Retry failed deliveries
• Send signed payloads

Option 2: Message broker fan-out

Best if downstream systems are internal.

• Publish to Kafka, SNS/SQS, Pub/Sub, RabbitMQ, etc.
• Each consumer subscribes to the topics it needs

Option 3: Hybrid

Common in payments:

• Core event stream goes to broker
• Webhooks are delivered from the same event log
• Analytics pipeline reads from the stream separately

Event schema suggestion

{
  "event_id": "evt_123",
  "event_type": "payment.succeeded",
  "created_at": "2026-10-05T12:34:56Z",
  "source": "payments-api",
  "account_id": "acct_456",
  "object": {
    "payment_id": "pay_789",
    "amount": 1250,
    "currency": "USD",
    "status": "succeeded"
  }
}

Practical recommendation

If you’re just starting:

• Store events in a durable database table
• Add an async delivery worker
• Support multiple destinations with per-destination configs
• Use HMAC-signed webhooks
• Add idempotency keys and retries

If you want, I can also help you design:

1. a database schema for event fan-out,
2. a webhook retry model, or
3. a Kafka/SQS-based architecture for this.