WebHooks act as stated by the Hollywood principle: Don't call us, we will call you!
Why should you care? Well Timothy Fitz explains it pretty well: webhooks offer the "simplest way for open integration between web services. You should care because webhooks will be ubiquitous. You should care because they’re going to reshape the internet. You should care because webhooks are the next step in the evolution of communication on the internet and nothing will be left untouched.
For example, lets say you want your application to respond when a loan get disbursed: just define a webhook in Mambu for the disbursement action and point the URL to your application. Mambu will POST a request to your app with all the information you request such as the loan account id, the client information and anything else. Your application can then respond to this request itself or call back to Mambu to request more information and trigger actions back in Mambu (such as creating a task and sending an email).
Based on client and partner testimonials it is confirmed that a robust implementation involves the balanced usage of webhooks. We are highly recommending webhooks usage for system to system notification purposes when the source of the events is Mambu core banking engine not an external system, case where Mambu ends up to be used as an orchestrator system which is out of the purpose of the core banking responsibility.