Klaviyo webhooks
Test and debug Klaviyo webhooksfor flows, segments and customer events
When customer events drive emails, segments and automations, a bad payload breaks more than a campaign. Capture and inspect every Klaviyo webhook before it does.
How Klaviyo webhooks work
| Where to create it | Webhooks API (Create Webhook) with a name, endpoint URL, topics and a secret key of at least 16 characters. The URL must start with https://, must not use a self-signed certificate and must not redirect. |
|---|---|
| Signature headers | Klaviyo-Signature: HMAC-SHA256 of the request body plus the Klaviyo-Timestamp value, keyed with your secret key. Klaviyo-Webhook-Id identifies the webhook. |
| Timeout | Respond with 200, 201 or 202 within 5 seconds, or the request counts as failed. |
| Retries | Exponential backoff with a maximum delay of 1 hour. A webhook left in an error state for over 48 hours is disabled. |
| Batching | One request can carry up to 1,000 events in its data array, possibly from several topics. |
Sources (checked November 2026)
See every Klaviyo webhook before it causes drift
Klaviyo webhooks often sit at the center of lifecycle flows, so one malformed event can affect segmentation, personalization and downstream automations.
Hooklistener gives marketing and engineering one event history, so you can inspect payloads, compare environments and replay (Pro) events while you check changes.
Where Klaviyo teams get stuck
Silent automation breakage
A single bad payload can send an event to the wrong flow or stop it from triggering at all, and the request disappears into logs.
Messy data mapping
When customer properties or event names change, troubleshooting turns into guesswork.
Slow cross-team debugging
Marketing wants answers quickly, but the fix often lives in engineering code, and the back-and-forth takes days.
How Hooklistener helps with Klaviyo webhooks
Inspect the Klaviyo event that broke a flow
Read the exact properties and headers of the Klaviyo webhook behind a welcome series that never triggered, instead of searching logs for a request that is already gone.
Anomaly detection for renamed properties
Anomaly detection flags missing fields, changed field types and new event types when a Klaviyo property or event name changes, before segments start drifting.
Shareable debugger links
Send marketing a link to the captured Klaviyo request so they and engineering look at the same payload, and use replay (Pro) to resend it once the fix is in.
Try it: point Klaviyo at a free webhook URL or run a test with the webhook tester.
Klaviyo webhook use cases teams rely on
Flow troubleshooting
Find out why a welcome series, browse abandonment flow or win-back automation did not trigger as expected.
Data hygiene checks
Confirm that names, properties and identifiers land in the format your segmentation rules expect.
Release checks
Test changes to event mapping or downstream integrations before a live campaign reveals problems.
Replay a failed webhook without re-triggering the provider
Once a delivery is captured, you can resend its exact headers and body to localhost, staging or production from the dashboard or through your coding agent over MCP, so the provider never has to fire a new event. Replay is on Pro and above. Read the replay guide.
Comparing webhook debugging tools?
See how Hooklistener stacks up against webhook.site, RequestBin, Beeceptor, Hookdeck and ngrok in the best tools to capture and inspect webhook payloads, or read the head-to-head pages for Hooklistener vs ngrok and Hooklistener vs Beeceptor.
Frequently asked questions
Can I inspect the full Klaviyo webhook payload?
Yes. Hooklistener captures the complete request so you can review the structure, properties and headers exactly as they were sent.
Can marketing use this without engineering?
Yes. Marketing can open a shareable debugger link to a captured event, while engineering takes over when a payload needs deeper troubleshooting.
Does this help with segmentation issues?
It does. When a property or event name changes, you can quickly confirm whether the webhook still matches the rules driving your flows.
Can I replay events to a staging endpoint?
Yes. Replay is on Pro and above. Resending a captured webhook to staging is one of the fastest ways to check mapping changes before you go live.
Make Klaviyo automations easier to trust
Capture the events behind your campaigns and inspect the payloads before you ship a change.