Push or Pull? Understanding Webhooks and APIs for Modern Applications

In modern software development, integrating systems is a common task. Whether you’re syncing user data, processing transactions, or triggering notifications, one question often comes up: Should I use a webhook or an API?

Both are valuable tools, but understanding how they work, their differences, and when to use each can save you from building inefficient or overly complex systems. Here's a straightforward guide to help you choose the right one.

API vs Webhook: What’s the Core Difference?

• API (Application Programming Interface): Your system initiates the request. It's a pull mechanism—you ask for data or perform actions when needed.

• Webhook: The external system initiates the request. It's a push mechanism—you get notified when something happens.

How They Work

APIs are request-driven. Think of them like placing an order at a service desk. You ask for data or initiate an action, and you get a response back.

const getUser = async (id) => {
  const res = await fetch(`/api/users/${id}`);
  const user = await res.json();
  return user;
};

You control:

• When to request data

• Which operations to perform (CRUD)

• How to handle the response

Webhooks are event-driven. Imagine receiving a message the moment something important happens, without having to ask.

app.post('/webhook/order', (req, res) => {
  const { orderId } = req.body;
  res.status(200).send("OK");

  // Handle the event
});

With webhooks:

• Data is sent to you automatically

• You react to events in real time

• No need for repeated polling

When APIs Make Sense

Use APIs when:

• You need data on-demand (e.g., displaying user profiles)

• You are performing complex, multi-step operations

• You require full control over create, read, update, and delete (CRUD) operations

• You are integrating deeply with third-party services

Example: A user clicks to view their profile → your app makes a GET request → shows the latest data.

When Webhooks Are the Better Choice

Use webhooks when:

• You need immediate notifications (e.g., a completed payment)

• You want to automate workflows based on real-time events

• You want to avoid inefficient polling

• You’re handling third-party services that offer webhook support

Example: Stripe sends a webhook after payment → your app updates the order → confirmation email is sent.

Security Considerations

APIs:

• Use OAuth, API keys, or JWTs for authentication

• Enforce rate limits to protect your endpoints

• Sanitize all inputs

• Always use HTTPS

Webhooks:

• Verify incoming requests using cryptographic signatures

• Handle retries and failures gracefully

• Use secure public endpoints and timeouts

Example for verifying a webhook signature:

const crypto = require('crypto');

app.post('/webhook', (req, res) => {
  const signature = req.headers['x-signature'];
  const expected = crypto.createHmac('sha256', process.env.SECRET)
    .update(req.body)
    .digest('hex');

  if (signature !== expected) {
    return res.status(403).send('Unauthorized');
  }

  // Proceed with processing
});

Local Testing Tips

APIs are easy to test using tools like Postman, curl, or your terminal.

Webhooks require a public endpoint. If you're developing locally, use a tunnel service to expose your local server with Pinggy. For example, a command like:

ssh -p 443 -R0:localhost:3000 a.pinggy.io

gives you a public URL that forwards to your local server, which is useful for testing services like Stripe, GitHub, or Twilio.

Webhooks vs WebSockets: Not the Same

While both are event-driven, they serve different purposes:

Webhooks notify systems about events. WebSockets maintain a live connection for continuous data flow.

When to Combine Both

Often, the best architecture uses both:

• Use webhooks for real-time alerts or triggers

• Use APIs to fetch full data or perform follow-up actions

Example: Webhook notifies you about an order → API fetches order details → backend updates status and sends notifications.

Summary Table

Conclusion

Webhooks and APIs serve different purposes, and choosing the right one can make your application more efficient, maintainable, and responsive. APIs give you precise control over when and what to request. Webhooks reduce overhead by pushing relevant events to you as they occur.

References

1. Webhook vs API: Differences and When to Use What?

2. APIs

3. Pinggy's Official Website