How do I receive inbound webhooks, validate them, and process them asynchronously?

A solid pattern is:

1. Expose a webhook endpoint
2. Verify the request is authentic
3. Return fast
4. Hand off work to a background queue
5. Process idempotently in a worker

Recommended flow

1) Receive the webhook

Your HTTP endpoint should do as little as possible:

• parse headers/body
• verify signature/authentication
• deduplicate if needed
• enqueue a job
• return 200 OK or 202 Accepted quickly

This keeps the sender from timing out.

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2) Validate the webhook

Validation usually includes:

• Signature verification using a shared secret or public key
• Timestamp check to prevent replay attacks
• Payload schema validation to ensure expected shape
• Source allowlisting if provider IPs are stable
• Idempotency / event ID deduplication to avoid double processing

Common signature schemes:

• HMAC over the raw request body
• timestamp + body signed with HMAC
• RSA/ECDSA signatures over the payload

Important: verify against the raw body, not a re-serialized JSON object.

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3) Process asynchronously

After validation, publish the event to a queue or job system:

• SQS
• RabbitMQ
• Kafka
• Redis Queue / BullMQ
• Celery / Sidekiq / Hangfire / etc.

Then have a worker:

• consume the event
• perform business logic
• retry on transient failures
• dead-letter permanently failing messages

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Example architecture

Webhook sender → Your API → Queue → Worker → Database / downstream systems

This gives you:

• fast HTTP responses
• retries
• resilience
• scaling independently for ingest and processing

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Example pseudocode

POST /webhooks/provider

raw_body = request.raw_body
signature = request.header["X-Signature"]
timestamp = request.header["X-Timestamp"]

if not is_valid_timestamp(timestamp):
    return 400

if not verify_hmac(raw_body, signature, secret):
    return 401

event = parse_json(raw_body)

if already_processed(event.id):
    return 200

enqueue("webhook-events", event)

return 202

Worker:

while true:
    event = dequeue("webhook-events")
    try:
        process_event(event)
        mark_processed(event.id)
    except transient_error:
        retry_later(event)
    except permanent_error:
        send_to_dead_letter(event)

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Best practices

Make processing idempotent

Webhook providers often retry delivery. Your worker should safely handle the same event multiple times.

Typical approaches:

• store event_id in a dedupe table with a unique constraint
• make state transitions conditional
• use upserts instead of inserts

Don’t trust the payload blindly

Even after signature verification:

• validate fields and types
• reject malformed data
• enforce expected event types

Preserve the raw payload

Store the original webhook payload and headers for debugging and audit.

Respond quickly

Aim to respond within a few hundred milliseconds if possible.

Separate “ingest” from “process”

The HTTP endpoint should only ingest and queue. Business logic belongs in workers.

Use retries thoughtfully

• Retry transient errors with exponential backoff
• Don’t retry invalid payloads
• Send poison messages to a dead-letter queue

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Minimal checklist

• HTTPS only
• Signature verification
• Timestamp/replay protection
• Schema validation
• Dedupe/idempotency
• Queue for async processing
• Worker with retries + DLQ
• Logging and metrics
• Store raw event for audit/debugging

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If you want, I can show this in a specific stack like Node.js/Express, Python/FastAPI, Go, or C#/.NET.