# Klaviyo Webhooks

## When to Use This Skill

* How do I receive Klaviyo webhooks?
* How do I verify Klaviyo webhook signatures (the `Klaviyo-Signature` header)?
* How do I handle Klaviyo system webhook events like `event:klaviyo.opened_email`?
* Why is my Klaviyo webhook signature verification failing?
* How do I secure a Klaviyo flow "Webhook" action that isn't signed?

## Verification (core)

Klaviyo signs each system webhook with an HMAC-SHA256 over the raw request
body concatenated with the `Klaviyo-Timestamp` header value, hex-encoded, using
your endpoint secret (min 16 chars). The signature arrives in the
`Klaviyo-Signature` header. Compute the same HMAC and compare timing-safe. There
is no official SDK verification helper, so verify manually. Pass the raw body —
don't `JSON.parse` first.

Node:

```javascript
const crypto = require('crypto');

function verifyKlaviyoWebhook(rawBody, timestamp, signature, secret) {
  const computed = crypto
    .createHmac('sha256', secret)
    .update(rawBody)        // Buffer/string of the raw HTTP body
    .update(timestamp)      // Klaviyo-Timestamp header value, appended
    .digest('hex');
  try {
    return crypto.timingSafeEqual(Buffer.from(computed), Buffer.from(signature));
  } catch {
    return false;           // length mismatch = invalid
  }
}

```

Python:

```python
import hmac, hashlib

def verify_klaviyo_webhook(raw_body: bytes, timestamp: str, signature: str, secret: str) -> bool:
    mac = hmac.new(secret.encode(), raw_body, hashlib.sha256)
    mac.update(timestamp.encode())          # append Klaviyo-Timestamp
    return hmac.compare_digest(mac.hexdigest(), signature)

```

> For complete handlers with route wiring, event dispatch, and tests, see:
> 
> * [examples/express/](https://github.com/hookdeck/webhook-skills/tree/main/skills/klaviyo-webhooks/examples/express/)
> * [examples/nextjs/](https://github.com/hookdeck/webhook-skills/tree/main/skills/klaviyo-webhooks/examples/nextjs/)
> * [examples/fastapi/](https://github.com/hookdeck/webhook-skills/tree/main/skills/klaviyo-webhooks/examples/fastapi/)

## Unsigned flow "Webhook" action

Signature verification above applies to system webhooks (created via the
Webhooks API). Klaviyo's older flow "Webhook" action sends a custom JSON
payload you define and is not signed. If signing is unavailable on your
account, put a hard-to-guess secret token in the endpoint URL (e.g.
`/webhooks/klaviyo?token=…`) and reject requests that don't match. See
[references/verification.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/klaviyo-webhooks/references/verification.md).

## Common Event Types (topics)

Each payload delivers a `data` array of events; every event carries a `topic`.

| Topic | Triggered When |
| --- | --- |
| `event:klaviyo.opened_email` | Recipient opened an email |
| `event:klaviyo.clicked_email` | Recipient clicked a link in an email |
| `event:klaviyo.bounced_email` | An email bounced |
| `event:klaviyo.marked_email_as_spam` | Recipient marked an email as spam |
| `event:klaviyo.unsubscribed_from_email_marketing` | Profile unsubscribed from email |
| `event:klaviyo.received_sms` | An inbound SMS was received |
| `event:klaviyo.sent_sms` | An SMS was sent |
| `event:klaviyo.submitted_review` | A review was submitted |

> For the full topic list, see [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/klaviyo-webhooks/references/overview.md)
> or call the [Get Webhook Topics](https://developers.klaviyo.com/en/reference/get_webhook_topics) endpoint.

## Environment Variables

```bash
KLAVIYO_WEBHOOK_SECRET=your_endpoint_secret_min_16_chars   # Set when creating the webhook

```

## Local Development

```bash
# Start tunnel (no account needed)
npx hookdeck-cli listen 3000 klaviyo --path /webhooks/klaviyo

```

## Reference Materials

* [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/klaviyo-webhooks/references/overview.md) - Klaviyo webhook concepts, full topic list, payload structure
* [references/setup.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/klaviyo-webhooks/references/setup.md) - Create a webhook via the API, get the endpoint secret
* [references/verification.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/klaviyo-webhooks/references/verification.md) - Signature verification details and gotchas