With the increase in web applications, and their use by growing numbers of remote and hybrid software teams, webhooks have become an indispensable tool for developers. This article introduces the concepts of webhooks, how they work, and how to use them. It also covers how webhooks differ from [APIs] and describes the webhooks service provided by CircleCI.

What is a webhook?

A webhook is a system that uses the HTTP protocol in real-time to notify other applications of specific events, such as updates to web applications or services.

Webhooks allow different software systems to communicate with each other automatically and immediately when certain actions occur. For example, For example, when a customer places an order on an website, a webhook can instantly notify the inventory management system to update stock levels and trigger a notification to the shipping department. This real-time communication enables efficient integration and automation between various applications and services, making software more responsive and dynamic.

How webhooks work

Webhooks are typically implemented using the HTTP protocol. By sending a POST request to a specific URL, typically to a particular endpoint, notifications are automatically sent to the receiving application or website. The receiving application processes the data contained within the request.

Webhooks mechanism

The operation of webhooks uses this mechanism:

  • The recipient of the webhook (an application) exposes an endpoint (URL).
  • The issuing service or application of the webhook sends a POST request to the endpoint when specific events occur.
  • The recipient of the webhook (the application) processes the posted data.

CircleCI webhook example

At CircleCI, we provide webhooks that integrate with a variety of tools. This allows you to aggregate job data in dashboards, send status alerts to various notification systems, trigger jobs from events outside of your code repository, and more, enabling flexibility in your development pipeline.

To get started using webhooks in your CI/CD pipelines, refer to the documentation.

CircleCI webhooks can be used for:

  • Analyzing and visualizing jobs and workflows on a dashboard
  • Visualizing and retrieving data using Airtable or other tools
  • Sending alerts for job statuses
  • Creating automation plugins and tools
  • Rerunning workflows using the API
  • Triggering jobs from events outside of the code repository

Learn more

How to use webhooks

With webhooks, you can streamline project status checks on a single communication app like Slack. Pull request notifications from GitHub, project-wide changes, code reviews, and request notifications can be picked up and communicated.

Using webhook-compatible services like Slack and Zapier enables integration with other services, like Twitter. This allows users to receive the correct information whether they’re using Slack, ChatWork, or something else.

Webhooks allow for data synchronization and customization of software or application functionality based on events.

APIs and webhooks: What’s the difference?

The primary difference between an Application programming interface (API) and webhooks is that APIs require manual periodic requests to fetch or modify data, while webhooks can automatically send data without requests from other applications based on specific events. This results in lower communication costs for webhooks compared to APIs.

Additionally, APIs are where clients make requests for data. If clients need more data or need to check for data updates, they must create separate requests. With webhooks, services (clients) are set up as endpoints for webhooks and provide these endpoints to other services.

Webhooks are suitable for applications or services that require real-time notifications. APIs are more appropriate for receiving information periodically or for processing tasks.

Services supporting webhooks

Many services support webhooks, like Jira, Dropbox, Trello, Zoom, and Google Drive.


Webhooks can be used in many ways, not just for development applications but also for apps needing real-time notifications, like communication apps, payment services, and stock price alerts. Using webhooks can provide other benefits by enhancing security and trustworthiness.

You can get started using webhooks in your development flow for free by signing up for a CircleCI account today.

Start Building for Free

Related Guides and Articles