Operations
Webhook
A webhook is an HTTP POST sent from one system to another when an event occurs — the modern alternative to polling. Examples: Stripe → your server on every charge, Calendly → your server on every booking, GitHub → your server on every commit.
More detail
Webhooks invert the API call direction. Instead of you constantly asking 'any new charges?', the source pushes you the data the moment it happens. Most modern SaaS supports webhooks. Best practice: respond 200 immediately + process async, verify signatures to prevent spoofing, implement idempotency keys for retries.