Churnkey Cancel Flow Embed
Client-side embed surface for personalized Cancel Flows. The JavaScript SDK is initialized with window.churnkey.init(), passing an appId, customerId, subscriptionId, provider, and a server-computed HMAC-SHA256 authHash (the customer ID signed with the Cancel Flow API key) so the hosted flow can be trusted. This is a client SDK plus HMAC authorization surface rather than a REST resource API.