Webhook, explained
A webhook is a way for one application to tell another that something happened. You give the sending system a URL, and whenever the event you chose occurs, such as a lead being created or a deal being won, it sends an HTTP POST request to that URL with the details in a JSON body. The receiving system then reacts: it drafts an invoice, updates a record or posts a note to a team chat.
The difference from a normal API call is direction. With an API, your system asks the other one for data, and to notice changes it has to keep asking. With a webhook, the other system tells you when something changes. Webhooks are efficient for exactly that reason, and they are how many platforms, including Meta Lead Ads and payment gateways such as Razorpay, notify other software about new events.
Webhooks need care to be dependable. The receiving end should check a signature to confirm the message is genuine, respond quickly, and handle the same event arriving twice without doing the work twice. The sending end should retry when the receiver is down and keep a log of failed deliveries. For example, a Chennai agency's CRM might send a deal won webhook to its billing tool, which drafts the first invoice. DigiPix Flow posts the events you choose to your HTTPS endpoint, signed, with failed deliveries retried and logged.