Hi @FrancoChoiz, welcome to the community!

As far as I know, you can’t use variables in the destination URL.  I tried, and it always returns an error for me.

However, you should note that there’s an upcoming beta feature of Klaviyo called “code action” that allows you to run a small code snippet as an action.  If you are doing something more complex than a simple webhook (including sending webhooks with dynamic URLs), that could probably be a great use case of it.  You can learn more (and sign up for the beta) here:

• (Beta) Add a code action to a flow

We’re not sure when this is going to be up for general release, so if your requirements are more immediate, perhaps a temporary workaround is you can build your own intermediary webhook receiver that you can have the Klaviyo Webhook call with all the data you need as part of the JSON payload, and then your app will simply relay it to final destination with the proper format.

Looking forward to see what you do so please update us here!