Webhook: the details
It’s an HTTP request carrying the event’s data: a confirmed payment, a created order, a signed document. The receiver replies right away with a success code and processes the work afterward. It’s the standard way to connect payment gateways, online stores, CRMs and e-signature tools to your own software.
Used well, it takes three precautions. Verify the signature that comes with each notification, to know it comes from who it says. Expect duplicates and disorder: providers retry when they get no reply, so the same event can arrive twice and the handling has to be idempotent. And log what was received, because when something doesn’t add up the first thing you need is to know what arrived and when.