Set or clear the store's public Klaviyo site ID
Authorizations
A secret API key. Publishable keys cannot reach this API. A key may carry an expiry, and an expired key is refused exactly like an unknown one, with a 401 that names no reason; check the key's expires_at in the dashboard rather than inferring it from a response. When a merchant rolls a key's secret they choose a grace window of up to 3 days, and for its duration BOTH the new secret and the one it replaced authenticate, so an integration moves over on its own deploy schedule instead of at the instant the button is pressed. Move before the window closes: after it, the old secret is refused. Nothing else about this contract moves with a roll. The key keeps its id and its scopes, so the only thing an integration updates is the credential itself.
Headers
A unique key per logical write. Replaying a request with the same key returns the first response byte for byte instead of applying the write twice.
Body
site_id IS REQUIRED BY NAME rather than defaulting to empty when omitted: sending an empty string clears the value on purpose, and an omitted field must not collapse into the same request. The value is public by design, the identifier baked into the onsite script URL every shopper's browser fetches, and this API already serves it unauthenticated at the storefront config route.
4 to 32 letters and digits, or empty to clear it.
Response
Success