I'm building an event-driven integration and need reliable inbound webhook handling

Reliable inbound webhook handling usually comes down to four things: authenticate, deduplicate, acknowledge fast, and process asynchronously.

Recommended flow

1. Receive webhook

   • Validate the request signature or secret token immediately.
   • Reject anything invalid with 401/403.

2. Acknowledge quickly

   • Return a 2xx as soon as the event is safely persisted.
   • Avoid doing business logic inline if it might take more than a few hundred milliseconds.

3. Persist the event first

   • Store the raw payload, headers, timestamp, and provider event ID.
   • This gives you an audit trail and a recovery path.

4. Deduplicate

   • Use the provider’s event ID, or construct an idempotency key from stable fields.
   • Enforce uniqueness at the database or queue level.

5. Process asynchronously

   • Push the event into a queue or job worker.
   • Your worker should be retryable and idempotent.

6. Handle retries safely

   • Webhook providers often retry on timeout or non-2xx.
   • Your endpoint should tolerate duplicates and out-of-order delivery.

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Core design principles

1) Idempotency

Assume the same webhook may arrive multiple times.

Do:

• Keep a unique constraint on provider_event_id
• Make downstream writes idempotent
• Use upserts where possible

Don’t:

• Trust “at least once” delivery to mean “once”

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2) Fast ACK

Webhook senders often expect a response within a short timeout.

Pattern:

• Verify
• Persist
• Enqueue
• Respond 200 OK

If processing is heavy, move it out of the request path.

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3) Signature verification

Use the provider’s recommended verification method:

• HMAC signature with shared secret
• Public-key verification
• Timestamp tolerance to prevent replay attacks

Check for:

• Body tampering
• Wrong secret
• Expired timestamps

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4) Replay protection

Store the event ID and a received-at timestamp. Reject:

• duplicates
• stale payloads outside your allowed window
• invalid signatures

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5) Observability

Add:

• request ID / event ID logging
• metrics for success, duplicate, invalid signature, processing failure
• dead-letter queue for poison messages

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Minimal architecture

Webhook endpoint

• Authenticates
• Saves event
• Emits job

Queue/worker

• Processes business logic
• Retries on transient failure
• Sends to dead-letter after max attempts

Database

• Stores raw webhook events
• Stores processed state / side effects

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Example pseudocode

def webhook_handler(request):
    body = request.raw_body
    sig = request.headers.get("X-Signature")

    if not verify_signature(body, sig, secret):
        return 403

    event = parse_json(body)
    event_id = event["id"]

    try:
        save_raw_event_once(event_id, body, request.headers)
    except DuplicateEvent:
        return 200

    queue.publish("process_webhook", {"event_id": event_id})
    return 200

Worker:

def process_webhook(job):
    event = load_raw_event(job["event_id"])
    if event_already_processed(event.id):
        return

    apply_business_logic(event)
    mark_processed(event.id)

---

Common pitfalls

• Doing side effects before persistence
• Not verifying signatures
• Returning 200 before the event is safely stored
• Assuming delivery order
• Not designing for duplicate delivery
• Missing dead-letter handling
• Logging secrets or full sensitive payloads

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Practical checklist

• Verify request authenticity
• Store raw event payload
• Deduplicate by event ID
• Return 2xx quickly
• Process asynchronously
• Make processing idempotent
• Retry transient failures
• Add dead-letter handling
• Monitor duplicates/failures
• Keep an audit trail

If you want, I can also give you:

1. a reference architecture for AWS/GCP/Azure,
2. a database schema for webhook event storage, or
3. an implementation example in Node.js, Python, or Go.