Track Calendly meetings with Google Tag Manager Web and Server

The Calendly meeting booking tool

Calendly is a free tool that lets your prospects book meetings online. It competes with Cal.com or Hubspot Meetings.

When you use Calendly, you can either use a Calendly page that displays your calendar, or embed it directly on your website through an iframe.

The GTM Web part of this article (the listener that detects the booking) only works if you have embedded Calendly on your website through an iframe (Inline embed, Popup widget or Popup text).

If you send your prospects straight to a Calendly page, this part does not apply, but the GTM Server variable described below also works from Calendly webhooks (see the “What about without an iframe?” callout).

I will now show you how to track Calendly meeting bookings and how to retrieve the data of the person who booked the meeting (email address, phone number, name, but also UTM parameters, booking form answers and payment data) to send it to advertising platforms.

Data flow overview

The diagram below gives an overview of the data flow that happens when a Calendly meeting is booked.

Install the Calendly listener in GTM Web

To listen to meeting bookings, you need to add this code in Google Tag Manager with a Custom HTML tag.

This is the classic listener that is easy to find online. It does not collect any user data, only the invitee URI (the person who booked a meeting). We will then use this URI in GTM Server to retrieve the information filled in by the invitee.

<script>
window.addEventListener('message', function(e) {
    if (e.data.event && e.data.event.indexOf('calendly.') === 0) {
        if (e.data.event === 'calendly.event_scheduled') {
            window.dataLayer = window.dataLayer || [];
            window.dataLayer.push({
                event: 'calendly_event_scheduled',
                invitee_uri: e.data.payload.invitee.uri
            });
        }
    }
});
/*
* v0.1.0
* Created by Data Marketing School at http://www.data-marketing-school.com
* Written by https://www.linkedin.com/in/lucasrollin/
*/
</script>

Copy the code above and paste it into a Custom HTML tag in GTM Web.

Example of a Calendly meeting booking

When a meeting is booked, the calendly_event_scheduled event is pushed to the dataLayer.

At this point, you have validated that the Calendly listener works properly and that the calendly_event_scheduled event is pushed to the dataLayer with the invitee URI.

The invitee URI always has this shape: https://api.calendly.com/scheduled_events/{event_uuid}/invitees/{invitee_uuid}. It contains both the meeting id and the invitee id, which is all the GTM Server variable needs.

dataLayer variable for the invitee URI

The invitee URI will be used server-side to retrieve the invitee’s data.

But before that, you need to create a dataLayer variable in GTM Web to access this value.

GA4 data flow

Google tag for GA4

In GTM Web, create a Google tag for your GA4 stream and fill in the measurement id of your GA4 property. If you don’t have one, or don’t plan to send data to GA4, you can use G-XXX.

In Configuration settings, fill in the server_container_url and send_page_view parameters.

GA4 event calendly_event_scheduled

Still in GTM Web, you then need to create a GA4 event tag to send the calendly_event_scheduled event to your GTM server.

To do so, fill in the server_container_url parameter with the URL of your GTM server.

Calendly variable in GTM Server

I developed a GTM Server variable, Enrich from Calendly API by DMS, that queries the Calendly API from the invitee URI and returns a single object gathering everything Calendly knows about the booking:

• the meeting details (event type name, start and end time, location, guests)
• the invitee’s user data (email, phone number, first and last name), already formatted for Google Ads, Meta or GA4 tags
• the UTM parameters passed to Calendly (utm_source, utm_medium, utm_campaign, etc.)
• the booking form answers and, when applicable, the routing form answers
• the payment data when the meeting is paid (amount, currency, transaction id)

Concretely, the variable makes up to three calls to the Calendly API: one for the meeting, one for the invitee and, if the invitee went through a routing form, one for their answers. Only the invitee call is mandatory: if the others fail, the variable still returns the rest of the data and logs the reason in the preview console.

Here is the shape of the object returned by the variable (keys missing in Calendly are simply omitted):

{
    // Meeting details
    name: "30 Minute Meeting",
    start_time: "2026-08-31T07:00:00Z",
    end_time: "2026-08-31T07:30:00Z",
    location: { type: "google_conference", join_url: "https://..." },
    invitees_counter: { total: 1, active: 1, limit: 1 },
    event_created_at: "2026-08-29T15:49:46Z",
    event_updated_at: "2026-08-29T15:49:50Z",

    // Invitee
    timezone: "Europe/Paris",
    created_at: "2026-08-29T15:49:46Z",
    updated_at: "2026-08-29T15:49:46Z",
    user_data: {
        email_address: "[email protected]",
        phone_number: "+33612345678", // if available
        address: {
            first_name: "John",
            last_name: "Doe"
        }
    },

    // UTM parameters passed to Calendly (if present)
    tracking: {
        utm_source: "newsletter",
        utm_medium: "email",
        utm_campaign: "webinar"
    },

    // Booking form answers
    event_questions: ["How did you hear about us?"],
    event_answers: ["A newsletter"],
    event_answers_by_question: { "How did you hear about us?": "A newsletter" },

    // Routing form answers (if the invitee went through a routing form)
    routing_form_questions: ["What is your budget?"],
    routing_form_answers: ["50k"],
    routing_form_answers_by_question: { "What is your budget?": "50k" },

    // Paid meetings only
    transaction_id: "ch_3Q7xKjL2eZvKYlo2",
    value: 150,
    currency: "EUR",
    payment_successful: true,
    payment: { provider: "stripe", amount: 150, currency: "EUR", ... }
}

A few details about how the user data is formatted:

• the email is cleaned up (spaces removed, lowercased), as expected by the conversion APIs
• the phone number is retrieved when available (SMS reminder or booking form answer)
• the first name and last name come from Calendly’s dedicated fields, or are split from the full name otherwise (a composed last name such as “de la Fontaine” is kept in full)
• for a paid meeting, transaction_id, value and currency are lifted to the top level so they can be used directly in a conversion tag

Import the variable from the GTM Server gallery

Go to the Variables section of GTM Server and click New.

Then click the blue banner at the top to open the variable template gallery.

Search for Calendly and click the Enrich from Calendly API by DMS template by Data Marketing School.

Then click Add to workspace to import the template into your GTM Server container.

Create a Calendly variable from the template

Go to the Variables section of GTM Server and click New to create a new variable.

Select the Enrich from Calendly API by DMS variable you just imported.

Once the variable is selected, you can see that there are 2 fields to fill in:

• Personal Access Token: a token you need to generate in your Calendly account so the variable can authenticate against the Calendly API.
• Invitee URI: an Event data variable you need to create in GTM Server to read the invitee_uri parameter sent by GTM Web.

Get the Personal Access Token in Calendly

In your Calendly account, go to the Integrations & apps section and click API and webhooks.

Then click Generate New Token in the Personal Access Token section.

When creating the token, Calendly asks you to choose the token’s scopes (permissions). Two scopes are useful for this variable:

• scheduled_events:read: required, it allows reading the meeting and the invitee
• routing_forms:read: optional, it allows reading the routing form answers. Without this scope, the variable still returns all the other data and simply reports the routing form error in the preview console

Then copy the generated token.

Then create a Constant variable to store this token in GTM Server.

Create the invitee_uri Event data variable

Next, you need to create an Event data variable to retrieve the invitee URI pushed to the dataLayer by GTM Web when a meeting is booked.

Complete configuration of the Calendly variable

You now have everything you need to configure the Calendly variable in GTM Server. All that’s left is to fill in the Personal Access Token field with the Constant variable you created to store the token, and the Invitee URI field with the Event data variable you just created.

Extract the user data from the Calendly object

The Calendly variable returns a complete object, but Google Ads, Meta or GA4 tags only expect the user_data object in the event’s user_data parameter. You therefore need to extract this property before injecting it into the event.

To do so, import the Object Property Extractor variable template from the GTM Server variable template gallery, the same way you did for the Calendly variable.

Then create a variable from this template. It has 2 fields:

• Object: select the Calendly variable you just configured
• Property: enter user_data

The Property field accepts dot notation to reach a nested property, for instance user_data.email_address if you only want the email address.

This variable only returns the user_data part of the Calendly object:

{
    email_address: "[email protected]",
    phone_number: "+33612345678", // if available
    address: {
        first_name: "John",
        last_name: "Doe"
    }
}

Enrich the calendly_event_scheduled event in GTM Server

The last configuration step consists in adding the Calendly data to the GA4 calendly_event_scheduled event when it is received in GTM Server. I’m using the user_data parameter as an example here, which will contain the invitee’s user data extracted with the Object Property Extractor variable you just created. But this is only an example: you can add any other data from the Calendly object the same way (UTM parameters, booking form or routing form answers, meeting amount, etc.), each with its own Object Property Extractor variable.

This is done by creating a Transformation of type Augment event.

In GTM Server, go to the Transformations section and click New to create a new transformation.

Then add a transformation of type Augment event.

Then configure the transformation so that it applies when the calendly_event_scheduled event is received. In the Parameters to augment section, add a new user_data field and set its value to the Object Property Extractor variable you configured earlier. Add as many fields as there are Calendly data you want to pass to your tags, one per Object Property Extractor variable.

Check the configuration

GTM Web preview

In the GTM Web preview, you can check two things:

1. the calendly_event_scheduled event is pushed to the dataLayer when a Calendly meeting is booked
2. the calendly_event_scheduled event is sent to the GTM server by the GA4 - Event - calendly_event_scheduled event tag you configured earlier

GTM Server preview

In the GTM Server preview, you can check that the calendly_event_scheduled event is received and that it contains the invitee_uri parameter.

In the Variables tab, also check that your Calendly variable is populated with the complete object (meeting details, user_data, tracking, form answers) and that the Object Property Extractor variable only contains the user_data part.

If the Calendly variable is undefined, open the Console tab of the preview: the variable logs the reason for the failure there. The most common cases are:

• Invalid URI: the invitee_uri parameter does not have the shape https://api.calendly.com/scheduled_events/{event_uuid}/invitees/{invitee_uuid}. Check the Event data variable and the GTM Web listener.
• 401: the Personal Access Token is missing, incorrect or has been revoked.
• 403: the token lacks the scheduled_events:read scope, or it was created by a member who is not the host of this meeting (see the callout about the admin role above).
• 404: the invitee no longer exists, for instance after a reschedule, which creates a new invitee with a new URI.

All the tags (Meta, Google Ads, etc.) you fire when the calendly_event_scheduled event is received in GTM Server can now access the invitee’s user data through the user_data parameter we added in the Augment Event transformation.

FAQ

Congratulations

You have now set up Calendly meeting tracking with Google Tag Manager Web and Server. You can now track meeting bookings and send your invitees’ user data to advertising platforms, and even use the UTM parameters, the form answers or the amount of paid meetings to go further.