> ## Documentation Index
> Fetch the complete documentation index at: https://docs.commenda.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Webhooks

> Receive real-time notifications about system events.

## Overview

Some actions initated over Commenda's API can trigger long-running asynchronous processes. Users of Commenda's API can receive updates when those processes complete by registering webhooks with the `/webhooks` collection of endpoints.

## Concepts

* **Topic**: A topic represents a category of notifications that your webhook can subscribe to. It groups related events under a single, descriptive label. Topics allow you to organize and filter the types of updates you want to receive.
* **Event**: An event is a notification that a specific action or change has occurred within Commenda's system. Each event belongs to a topic and carries detailed information about the triggering action or change.

### How To Use Webhooks

* **Topic Subscriptions:** Each webhook can listen to one or more topics, and multiple webhooks can subscribe to the same topic.
* **Security Validation:** Webhook users must validate that their received messages were actually sent by Commenda. Commenda uses the **HMAC SHA256** scheme to validate webhook payloads. A `Commenda-X-Secret` header will be attached to every event payload. Learn more about HMAC SHA256 [here](https://webhooks.fyi/security/hmac). If you need any help with this, please contact the Commenda team.
* **Event Objects:** Every time Commenda sends a request to your webhook URL, it includes an event object. You can read more about event objects [here](https://docs.commenda.io/engine/indirect-tax/webhooks/event.md).

***

## Getting Started

1. **Register Your Webhook**

   * Create a new webhook for a specific topic by making a `POST` request to the `/webhooks` endpoint.

2. **Test Your Webhook**

   * You can manually trigger a webhook call using the `POST /webhooks/test/trigger/:id` endpoint. More details are available [here](https://docs.commenda.io/engine/indirect-tax/webhooks/webhooks-TEST.md).

3. **You're All Set**

   * Once your webhook is registered, you'll start receiving updates for the topics you've subscribed to.

4. **Manage Your Webhook**

   * To update your webhook details, use the `POST /webhooks/:id` endpoint.
   * To delete a webhook, use the `DELETE /webhooks/:id` endpoint.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.