We have a Flowstep called 'External Data', which you can apply to a Flow. The External Data Flowstep can e.g., send JSON, XML, or form data to another application, something you would also want to do with a Webhook:
In addition, Flowmailer Pro also allows you to apply a Webhook-alike mechanism when it comes to messages event. This is called 'Event Flows' in Flowmailer, where you can easily push message events (opens, clicks, bounces) to another application (Webhook):