What Are Webhooks? And How They Differ From APIs
📷 anshul kumar · Pexels✦ Key takeaways
- A webhook pushes data the instant an event happens, without you asking (push model).
- A traditional API relies on repeatedly polling for updates (pull model).
- Webhooks are faster and lighter for real-time events like payments or messages.
- You need a public URL to receive requests, and you should verify each request's authenticity.
A webhook is a way for one app to automatically notify another the moment a specific event happens. Instead of your app repeatedly asking a payment service every few seconds "has a purchase happened?", the payment service itself sends a message to a URL you specified the instant a purchase occurs. That's why it's sometimes called a "reverse API".
An analogy: imagine you're waiting for a package. A traditional API is like phoning the courier every hour to ask "has my package arrived?" — many calls, most with no news. A webhook is like asking them to call you once, the instant it arrives. The first is the polling (pull) model; the second is the push model.
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How does it work in practice? You register a public URL with the service (say, a payment gateway or messaging platform). When the event occurs, the service sends an HTTP POST request to your URL carrying the event data, usually as JSON. Your server receives the request, verifies it, and then does what's needed — sending a receipt or updating the database.
| Factor | Webhook (push) | Polling API (pull) |
|---|---|---|
| Who starts the connection | The sending service | Your app |
| Timing | The instant the event happens | Every fixed interval |
| Resource use | Low | High (many empty requests) |
| Latency | Near-instant | Delayed by the poll interval |
| Best for | Real-time events | Slowly changing data |
Where are webhooks used? Almost everywhere: telling your store a payment succeeded (Stripe, PayPal), alerting your team to a new message (Slack), triggering a build when new code is pushed (GitHub), or connecting your apps through automation platforms. All rely on webhooks to move events instantly.
An important security note: because your URL is public, anyone could try to send fake requests to it. So serious services send a secret signature with each request, and your server must verify it before trusting the data. Skipping this verification is a common security hole.
Bottom line: webhooks and APIs aren't rivals but complementary tools — use webhooks for real-time events you don't want to wait for, and APIs when you need to request data at a time of your choosing.
Sources
Osama AbdelAal is the founder of Marifa, a digital-marketing and entrepreneurship expert and Hootsuite EMEA Ambassador. He oversees and reviews Marifa’s editorial content to ensure it is accurate, clear and genuinely valuable.