Webhooks

Webhooks offer a great way to automate the flow with other apps when invitees schedule, cancel or reschedule events, or when the meeting ends. The webhook subscription allows you to listen to specific trigger events, such as when a booking has been scheduled, for example. You can always listen to the webhook by providing a custom subscriber URL with your own development work. However, if you wish to trigger automations without any development work, you can use the integration with Zapier which connects Cal.com to your apps.

Creating a webhook subscription

To create a new webhook subscription, visit /settings/developer/webhooks and proceed to enter the following details:

1. Subscriber URL: The listener URL where the payload will be sent to, when an event trigger is triggered.

2. Event triggers: You can decide which triggers specifically to listen to. Currently, we offer listening to Booking Cancelled, Booking Created, Booking Rescheduled and Meeting Ended.

3. Secret: You can provide a secret key with this webhook and then verify it on the subscriber URL when receiving a payload to confirm if the payload is authentic or adulterated. You can leave it blank, if you don't wish to secure the webhook with a secret key.

4. Custom Payload: You have the option to customize the payload you receive when a subscribed event is triggered.

Creating a webhook

Verifying the authenticity of the received payload

1. Simply add a new secret key to your webhook and save.

2. Wait for the webhook to be triggered (event created, cancelled, rescheduled, or meeting ended)

3. Use the secret key to create an hmac, and update that with the webhook payload received to create an SHA256.

4. Compare the hash received in the header of the webhook (X-Cal-Signature-256) with the one created using the secret key and the body of the payload. If they don't match, the received payload was adulterated and cannot be trusted.

Adding a custom payload template

Customizable webhooks are a great way reduce the development effort and in many cases remove the need for a developer to build an additional integration service.

An example of a custom payload template is provided here:

{
    "content": "A new event has been scheduled",
    "type": "{{type}}",
    "name": "{{title}}",
    "organizer": "{{organizer.name}}",
    "booker": "{{attendees.0.name}}"
}

where {{type}} represents the event type slug and {{title}} represents the title of the event type. Note that the variables should be added with a double parenthesis as shown above. Here’s a breakdown of the payload that you would receive via an incoming webhook, with an exhaustive list of all the supported variables provided below:

Webhook variable list

Variable	Type	Description
triggerEvent	String	The name of the trigger event [BOOKING_CREATED, BOOKING_RESHEDULED, BOOKING_CANCELLED, MEETING_ENDED]
createdAt	Datetime	The Time of the webhook
type	String	The event type slug
title	String	The event type name
startTime	Datetime	The event's start time
endTime	Datetime	The event's end time
description	String	The event's description as described in the event type settings
location	String	Location of the event
organizer	Person	The organizer of the event
attendees	Person[]	The event booker & any guests
uid	String	The UID of the booking
rescheduleUid	String	The UID for rescheduling
cancellationReason	String	Reason for cancellation
rejectionReason	String	Reason for rejection
team?.name	String	Name of the team booked
team?.members	String[]	Members of the team booked
metadata	JSON	Contains a metadata of the booking, including the meeting URL (videoCallUrl) in case of Google Meet and Cal Video

Person Structure

Variable	Type	Description
name	String	Name of the individual
email	Email	Email of the individual
timezone	String	Timezone of the individual ("America/New_York", "Asia/Kolkata", etc.)
language?.locale	String	Locale of the individual ("en", "fr", etc.)