What Is a Webhook and Why Do You Need It?

What Is a Webhook?
Alex Kachalov Alex Kachalov 01 august 2022, 20:28 536
For beginners

You've probably already heard of webhook integrations in some of your apps but aren't sure what they are or whether you should use them.

What Is a Webhook?

According to data from Google Trends, webhooks have become more popular over the last five years. But while they're clearly in demand, what exactly are they, and what do they mean for businesses that send emails?

What Is a Webhook?

A webhook is a programming interface that is driven by events instead of requests. It allows one program to send data to another as soon as a specific event occurs. Since the communication is initiated by the app sending the data rather than the one receiving it, webhooks are often called "reverse APIs."

Assume you want to be notified via your company’s messaging system whenever a specific product is mentioned in a blog or a specific hashtag is used. Instead of regularly querying the blogging platform for new posts that meet these criteria, the latter may send a notification only when this event occurs. The purpose of a webhook is to allow the receiving app to sit back and have the data it requires without sending repeated requests to another system.

Webhooks are a popular lightweight solution for real-time notifications and data updates without having to develop a full-scale API for interconnecting web services.

What Is a Webhook?

Using webhooks is extremely effective because everything is decoupled. System B, which receives the notification via the chosen URL, is not only aware of the event on another system, but can also respond to it.

Why a POST request, in particular? Because it allows you to include a body in the request. It is usually a simple JSON object, but it could also be an XML document. This will always be specified in the webhook documentation, so be sure to study it before getting started.

The information needed to know what happened is found directly in the body. It will also tell you which user triggered it when it happened and other details about the event.

An added benefit is that webhooks can be public or private. The owner of a specific system's account can register a webhook as private. It is not possible to track the account's activities in the wild.

APIs vs. Webhooks

APIs and webhooks are often mentioned in similar contexts. And while they can both help you achieve your goals, they are not the same.

An application programming interface (API) is another tool that helps different apps communicate with one another. Although their use cases are very similar, you need to know the primary difference between APIs and webhooks.

It has to do with how they send and receive information.

Pushing vs. Pulling

The “pulling” process helps obtain data from an API. This is when your application sends a request to an API server to check for new data. In contrast, a webhook allows providers to send ("push") data to your application only when an event does occur. APIs are used to periodically pull data from a server in order to stay current. With webhooks, however, the server can push this data to you via webhooks as soon as something happens.

Pushing vs. Pulling

APIs are like you calling an electronic store repeatedly to see if they have a new smartphone model you’d like. Webhooks are like asking the store to call you back when they have the smartphone in stock, which saves both time and resources.

Webhooks are less resource-consuming because they save you time by not having to keep constantly checking for new data.

So, why use APIs at all if webhooks are easier to set up, less resource-intensive, and faster than APIs?

APIs are still widely used for various reasons:

  • Not all applications support webhook integrations.
  • Webhooks can only send you notifications about events; if you want to make changes based on new data or modified objectives, you'll need an API.
  • A webhook payload might not have all the information you require about an event.

APIs are still handy, and many apps support both APIs and webhooks.

Why Do You Need to Use Webhooks?

Assuming you're running a membership site. You must manually enter a customer's information into your membership management application every time they pay you through a payment gateway like Visa. As the number of new members grows, this task becomes even more tedious. But what if Visa and your membership management software could communicate? Can anyone who pays with a Visa card be automatically added as a member?

One way to accomplish this scenario is via a webhook. Assume Visa and your management software both have webhook integrations. The Visa integration can then be set up to automatically transfer a user's information over each time a payment occurs.

Here's an example of how this could work:

Why Do You Need to Use Webhooks?

Webhooks are a fantastic technology that saves you time and effort. Due to their popularity, you'll be able to integrate most of the web apps you're already using.

Connecting your email marketing software to other applications via a webhook can open up a whole new world of possibilities:

  • You connect a payment service to your email marketing software via a webhook so that when a payment bounces, the customer receives an email.
  • Webhooks can help you sync customer data across multiple applications. For example, if a user's email address changes, you can make sure the change is reflected in your CRM.
  • You can use webhooks to send event data to external databases or data warehouses for further analysis.

Consuming a Webhook

Giving the webhook provider an URL to deliver requests to is the first step in consuming a webhook. The most common method is to use a backend panel or an API. You'll need to create an URL in your app that can be accessed from the internet.

The majority of webhooks will send you data in one of the following formats: JSON (usually), XML (blech), or form data. These are simple to understand, and most web frameworks will take care of the rest.

UniOne’s Web API methods only accept HTTPS POST requests in JSON format with a maximum size of 10 megabytes and return JSON responses. In the event of an error, a suitable HTTP code is returned in addition to the JSON body with the error description. API endpoint (or base URL) must be sent to the server that matches the user's registration server:

Calling any method requires authentication with the user's or project's API key, using either of these two methods:

  • The X-API-KEY HTTP header;
  • The api_key JSON field in the request body.

You can find your API key on the settings page.

When an App Doesn’t Have Webhook Integrations

Despite their popularity and importance, some applications do not support webhooks. This can be mitigated with middleware apps such as Zapier, IFTTT, and Automate.io that can be used to regularly "pull" APIs and send updates via webhooks. You can use them to connect apps that don't have native webhook integrations and share data between them.


Webhooks are an important component of the internet that is currently growing in popularity. They enable your applications to communicate with one another in real time.

While webhooks and APIs are very much alike, they serve different purposes and have different use cases. The best way to learn about webhooks is to use them for yourself. To get a feel for it, create a few webhook connections between your applications.

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