Webhooks vs API: What's the Difference?
Webhooks and APIs both move data between systems, but one pulls and the other pushes. A clear explanation of webhooks vs APIs, when to use each, and how they work together.
If you're integrating two systems, you'll hit this question fast: should you call an API, or receive a webhook? They both move data over HTTP, but they work in opposite directions — and picking the right one saves you a lot of wasted requests.
The one-line answer
- API: you pull. Your app asks the other system for data when it needs it.
- Webhook: they push. The other system sends you data automatically when something happens.
How an API works (pull)
With a typical web API, your application is the one making requests. You want to know if an order shipped, so you call the provider's endpoint and get the current state back:
GET /v1/orders/ord_123
# -> { "status": "shipped" }
If you want to stay up to date, you have to keep asking — polling every minute or so. Most of those requests return "nothing changed," which wastes time and rate limits.
How a webhook works (push)
A webhook flips the direction. You give the provider a URL, and they send you an HTTP POST the moment an event occurs:
POST /your-webhook-endpoint
Content-Type: application/json
{ "event": "order.shipped", "id": "ord_123" }
No polling, no wasted calls — you find out as it happens. That's why webhooks are sometimes called "reverse APIs" or "push APIs." (New to them? See what is a webhook.)
Webhooks vs API at a glance
| API (pull) | Webhook (push) | |
|---|---|---|
| Who initiates | Your app | The provider |
| Timing | On demand / polled | Real time, event-driven |
| Efficiency | Wasteful if polling | Only fires on events |
| Needs a public URL | No | Yes (a URL providers can reach) |
| Best for | Fetching current state | Reacting to events |
| Failure handling | Retry your own call | Provider retries delivery |
When to use which
Reach for a webhook when:
- You need to react to events in near real time (payments, deploys, new messages).
- You'd otherwise be polling an API constantly.
Reach for an API (or polling) when:
- The provider doesn't offer webhooks.
- You need a full, current snapshot on demand.
- You only need the data occasionally.
They're better together
The most robust integrations use both. A common, reliable pattern is the thin event: the webhook tells you that something happened, and you call the API to fetch the authoritative details.
order.shipped webhook arrives -> GET /orders/ord_123 to fetch full, current data
This avoids trusting a payload that might be stale or out of order, and keeps your webhook handler simple.
The catch with webhooks: you need a reachable URL
The one thing a webhook needs that an API call doesn't is a public URL the provider can POST to — which is awkward when your code runs on localhost or behind a firewall. That's exactly what Webhook Relay solves: inspect the payload in your browser, then forward it to localhost or a private server with no public IP.