Webhook
An HTTP callback another system fires at your endpoint when an event happens — the standard way platforms push real-time updates without polling.
· Reviewed by senior engineers
A webhook is an HTTP request another system sends to your URL when something happens — an order paid, a customer created, an email bounced, a build finished. Webhooks let you react to events without polling, which is cheaper, faster and more scalable than asking "anything new?" every minute.
Every serious SaaS exposes webhooks now: Shopify, Stripe, GitHub, Slack, Salesforce, Klaviyo, Twilio. Your endpoint becomes a small inbox that processes events as they arrive. Done well, webhooks are the connective tissue of modern integrations.
The failure modes are predictable and important. Webhooks are at-least-once, not exactly-once — duplicates happen and your handler must be idempotent. They can arrive out of order. The sender will retry on failure, sometimes aggressively. Signature verification is mandatory or anyone with the URL can forge events. Long-running handlers time out; the right pattern is to acknowledge quickly and process in a background job. And on volume spikes, you need a queue between the webhook endpoint and the worker, or you'll drop events.
Devinsta builds webhook receivers as durable, observable, idempotent pipelines — usually a Vercel/Cloudflare edge function or AWS Lambda that signs-verifies, enqueues to SQS or Inngest, returns 200, and processes async. Every integration is one webhook regression away from quiet data loss; the architecture has to assume that.