Webhooks vs REST APIs: when to use one over the other

As you look to integrate applications and sync data, you’ll have a number of considerations to address.

At the top of your list is likely deciding between webhooks and REST APIs.

Each comes with distinct advantages and disadvantages, which can leave one better suited than the other for specific integration scenarios.

To help you use webhooks and REST APIs effectively over time, we’ll define each, review their respective advantages and disadvantages, and compare them directly.

Related: How to choose between webhooks and API polling

What is a webhook?

It’s a mechanism that allows applications to send real-time data or events to one another over the internet.

Here’s a bit more on how it works: An application (the destination system) registers a webhook endpoint in another application (the source system) that specifies the application that wants to receive the data/notification and the information it wants to receive. Once the event occurs, the source system makes a POST request to the webhook endpoint; the destination system then processes the data within the POST request, which can potentially trigger additional actions within the application.

Pros of using webhooks

Here are some of the advantages of using webhooks:

  • Allows applications to receive data in real-time. This is especially critical for certain use cases, such as routing leads to sales reps or sending urgent issues to engineering 
  • Lets you avoid unnecessary API calls. API polling, which makes repeated requests to an endpoint and compares every new response with the previous one to determine if there’s new information, can be costly and requires extensive error handling over time. Webhooks let you avoid these drawbacks, making them more cost-effective and easier to manage.
  • Addresses a wide range of use cases. A variety of applications support webhooks. As a result, numerous teams can leverage them for their respective use cases.

Cons of using webhooks

Webhooks also come with disadvantages:

  • Data or notifications may not always be sent to the destination system. If the source system experiences downtime, it might not capture the relevant data or notifications; when this happens, the notifications or data won’t get sent to the destination system.
  • Certain applications may not support webhooks. This naturally prevents you from using them for those systems.
  • Their functionality is inherently limited. Webhooks only allow you to send data or notifications in one direction. It doesn’t support bidirectional data flows or additional HTTP methods, like DELETE or GET.

Related: How to set up webhooks across your integrations

What is a REST API? 

A REST (representational state transfer) API follows the constraints of the REST architectural style. 

More specifically, REST APIs provide a standardized way for applications to request information from and send information to one another. This includes creating, reading, updating, or deleting a specific resource (i.e. a specific type of data or object) via HTTP methods.

Pros of REST APIs

Here are some of the advantages of using REST APIs:

  • They are widely available. The vast majority of applications you want to connect to will offer web APIs, and REST APIs are the most popular type of web API.
  • They support CRUD operations. In other words, you can take a variety of actions on the resources to address your needs. 
  • They are format-agnostic. Since they use the HTTP standard, they can represent resources in multiple formats, from XML to JSON.

Cons of REST APIs

Here are some drawbacks to keep in mind:

  • Data can’t be shared in real-time. This can prevent REST APIs from working effectively for very time-sensitive scenarios. 
  • Can force you to make unnecessary API calls. Using REST APIs, you don’t know when, exactly, a resource gets created, modified, or deleted. This can lead you to make API calls when there haven’t been any changes to the resource; over time, these needless calls can come at a high cost.
  • Time-intensive to build and maintain REST API connections. Each vendor’s REST APIs are unique, whether that’s related to authentication, rate limits, pagination, etc. A developer needs to account for all these differences as they build to the providers’ endpoints. Moreover, the developer needs to keep tabs on—and potentially respond to—any changes vendors make to their APIs to ensure the connections aren’t adversely impacted. 

So, given all the pros and cons of webhooks and REST APIs, which should you use? We’ll address this question head on in the following section.

Related: A guide to REST API integration

Webhooks vs REST API

If you need to receive data or notifications in real-time, you should look to use webhooks. But if there isn’t a time-sensitive need for the data or notifications, or your integration requirements extend beyond POST requests, REST APIs are likely a better approach. 

Build integrations with webhooks and REST APIs at scale with Merge

Merge, the leading unified API platform, lets you build to a single unified API to access a whole category of integrations—from CRM to HRIS to ATS to file storage—for your product. 

Through the product integrations built in Merge, you can sync data in various frequencies, which include real-time (via webhooks) syncs, time-based (via API polling) syncs, or ad-doc syncs.

Learn more about Merge by scheduling a demo with one of our integration experts.