Source type

Klaviyo Source Configuration

Klaviyo sources receive system webhook events and verify Klaviyo's signature and timestamp headers.

KLAVIYOPOST, PUT, PATCH, DELETEHMAC SecretEmail and messaging
Klaviyo system webhooks documentationAll source types
Klaviyo sends webhook traffic to a FastHook source, FastHook validates the provider contract, records the request, and routes accepted events through connections to destinations.KlaviyoProviderPOST, PUT, PATCH, DELETESignedFastHookSource URLKLAVIYOProvider credentialsignatureVerify before queue401 on auth failure405 on wrong methodAcceptedRequestverified: trueConnections route the accepted request to destinationsFilters, transformations, retries, replay, and destination signatures stay downstream from source verification.

Klaviyo configuration

Create a Klaviyo source, keep POST and PUT and PATCH and DELETE enabled, and provide the configured HMAC Secret values for provider signature. FastHook uses these settings to validate each Klaviyo delivery before it enters the routing workflow.

Source Type

KLAVIYO

Allowed methods

POST, PUT, PATCH, DELETE

Authentication

Provider signature

Credential fields

HMAC Secret

Klaviyo source config
{
  "type": "KLAVIYO",
  "config": {
    "auth_type": "PROVIDER_SIGNATURE",
    "auth": {
      "provider": "KLAVIYO",
      "webhook_signing_secret": "provider-secret"
    },
    "allowed_http_methods": ["POST","PUT","PATCH","DELETE"]
  }
}

Klaviyo request contract

FastHook signs raw body + timestamp with HMAC-SHA256 and compares the hex digest to klaviyo-signature.

POSTPUTPATCHDELETE

Klaviyo headers

Preserve klaviyo-signature, klaviyo-timestamp when sending Klaviyo test deliveries. FastHook evaluates this request context before accepting the payload, so missing or modified values remain visible as rejected requests instead of routed events.

klaviyo-signature

HMAC-SHA256 hex signature.

klaviyo-timestamp

ISO/RFC timestamp included in the signed payload.

Klaviyo setup

  1. Create a Klaviyo system webhook with the FastHook Source URL.
  2. Paste the HMAC secret into FastHook.
  3. Route by metric, event, or object fields in the Klaviyo payload.

Continue with Klaviyo