The Problem: How Does App A Know When Something Happens in App B?
When you're connecting two applications — say, a payment processor and your CRM — one app needs to know when something happens in the other. There are two fundamental approaches to solving this: polling and webhooks. Understanding the difference matters whether you're choosing an integration platform or building one yourself.
What Is Polling?
Polling is the simpler, older approach. Your application periodically sends a request to another service asking, "Has anything changed?" — like a child in the back seat asking "Are we there yet?" every five minutes.
How it works:
- App A sends a GET request to App B's API: "Give me all new orders since 10 minutes ago."
- App B responds with the data (or an empty response if nothing changed).
- App A waits the defined interval, then repeats.
Pros of Polling:
- Simple to implement — just a scheduled HTTP request
- Works with any API, even those that don't support webhooks
- Your app controls the timing
Cons of Polling:
- Inefficient: Most requests return nothing. You're hitting the API constantly for no reason.
- Latency: If you poll every 5 minutes, an event could wait up to 5 minutes before being acted upon.
- API rate limits: Frequent polling can hit rate limits quickly, especially on free-tier APIs.
What Are Webhooks?
Webhooks flip the model. Instead of App A asking App B for updates, App B tells App A when something happens. It's the difference between calling a restaurant every hour to ask if your table is ready versus asking them to call you when it's ready.
How it works:
- You register a webhook URL (an endpoint on your server) with App B.
- When an event occurs in App B (e.g., a payment is completed), it sends an HTTP POST request to your URL with the event data in the body.
- Your app receives and processes the payload immediately.
Pros of Webhooks:
- Real-time: Events are delivered within milliseconds of occurring.
- Efficient: No wasted requests — your server only receives data when something actually happens.
- Scalable: Works well even with high event volumes.
Cons of Webhooks:
- Requires a publicly accessible endpoint (your server must be reachable from the internet).
- You need to handle failures — if your server is down when a webhook fires, you may miss events.
- Security requires verification: always validate webhook signatures to prevent spoofed requests.
Side-by-Side Comparison
| Aspect | Polling | Webhooks |
|---|---|---|
| Initiator | Your app asks | Remote app notifies |
| Latency | Depends on interval | Near real-time |
| Efficiency | Low (wasted requests) | High (event-driven) |
| Setup complexity | Low | Moderate |
| Requires public URL | No | Yes |
| Works offline/queue | Yes | Requires retry logic |
When to Use Each
Use polling when: the API doesn't support webhooks, you need compatibility with legacy systems, or you're prototyping quickly and latency isn't critical.
Use webhooks when: you need real-time responses (payment confirmation, form submissions, inventory updates), you want efficient API usage, or you're building production-grade integrations.
Practical Tip: Using Webhooks with Zapier or Make
Both Zapier and Make (Integromat) support webhook triggers. You can create a webhook URL within these platforms and use it as the notification endpoint for any app that supports outgoing webhooks — no server required. This is one of the fastest ways to build real-time, event-driven integrations without writing code.
Summary
Polling is simple but wasteful. Webhooks are efficient and real-time but require a bit more setup. For most modern app integrations, webhooks are the preferred architecture. Understanding this distinction will help you make better decisions when evaluating integration tools and designing automated workflows.