AnyTrack Identifiers

This page is the complete reference for the identifiers AnyTrack uses to connect a visitor, their actions, and the conversions they generate across your marketing stack.

If you want to understand how the Click ID stitches a customer journey together, see AnyTrack Click ID. If you want to send events without the Tracking Tag, see Server-Side Client ID.

Quick reference

Identifier	Parameter	What it identifies	Granularity
Client ID	cid	The visitor (anonymous)	One per visitor cookie
Page Click ID	atclid	The page session	One per page load (30 characters)
Click ID	click_id	A specific action or trackable element	One per link, form, or cart (34 characters)
External ID	refId	An external alias you control	One per customer record
Property ID	{propertyid}	The tracked website	One per AnyTrack property
Tracking Group	tgid	An integration or group of links	One per integration

Quick mnemonic: cid is who, atclid is which page, click_id is which action, refId is your own name for them.

Core identifiers

These four identifiers carry the visitor and their actions through AnyTrack.

Identifier	Parameter	Definition	Where it is generated
Client ID	cid	A cookie ID that anonymously identifies the visitor. A 14-character alphanumeric string.	Set as a first-party cookie by the Tracking Tag, or minted server-side via the collect endpoint.
Page Click ID	atclid	A 30-character click ID for the current page session. Not tied to a specific element.	The Tracking Tag generates it when a page loads.
Click ID	click_id	A 34-character click ID for a specific trackable element (a link, form, or cart) or a server-side event. The 4 characters added to the atclid identify the element. This is the value that travels between platforms.	The Tracking Tag appends it per element through AutoTag. Server-side it is the Property ID joined to the cid: {propertyid}{cid}.
External ID	refId	An external alias for a cid, such as an email, phone number, or your own customer ID.	You supply it when the click_id cannot reach a destination such as a CRM.

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Client ID vs Click ID

The cid identifies the visitor. The click_id identifies an action that visitor performed. Every event attribute (customer data, transaction details, product data) attaches to the click_id, not the cid.

Structural identifiers

These identifiers describe your account setup rather than a single visitor.

Identifier	Parameter	Definition
Property ID	{propertyid}	Identifies the property (website) being tracked. It forms the prefix of every Click ID.
Tracking Group	tgid	References an integration or a group of links so AutoTag knows which links and forms to append the Click ID to. Examples: typeform, ghl.

How the Click ID is structured

The AnyTrack Click ID is composed of three strings that let AnyTrack rebuild the visitor timeline:

Property unique identifier	Visitor unique identifier	Encrypted key
IBTO9lOfAMybr	KiiB1U9YG91IF	js3Dv9AV

The full value looks like IBTO9lOfAMybrKiiB1U9YG91IFjs3Dv9AV. The page-level atclid is the first 30 characters. A click_id extends it to 34 characters, where the final 4 characters identify the specific element (such as an affiliate link or a form). In server-side setups, the Click ID is the Property ID concatenated with the cid you generated: {propertyid}{cid}.

Where identifiers are generated

Client-side (Tracking Tag)

When the Tracking Tag runs in the browser, it sets the cid cookie, generates the atclid for the page, and appends a click_id to each trackable element through AutoTag.

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Note

PageView is the only standard event that does not generate a click_id by default. See Standard Conversions for the full event list.

Server-side (collect endpoint)

When the Tracking Tag cannot run (Facebook Lead Ads, offline conversions, headless checkouts, or a contact created directly inside a CRM), AnyTrack creates the session server-side. You generate a 14-character cid, send a PageView to the collect endpoint, and the click_id becomes {propertyid}{cid}. See Server-Side Client ID for the full payload.

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HubSpot CRM contacts

When a contact is created directly in the HubSpot CRM interface, the AnyTrack app for HubSpot generates a server-side Client ID for that contact. This lets AnyTrack track the contact even though no browser session existed at creation.

How the Click ID travels

A Click ID moves through four stages. A single platform can act at more than one stage.

1. Generation — the Tag (client-side) or the collect endpoint (server-side) creates the identifier.
2. Propagation — AutoTag appends the Click ID to links and embeds, a hidden form field or action URL carries it through the --CLICK-ID-- token, or an integration (or Zapier or Make) passes it along.
3. Landing — the destination stores the Click ID value in a field, such as a CRM contact property.
4. Matching — the conversion returns to AnyTrack through a native integration event or a webhook, and AnyTrack matches it back to the original session by the click_id, or by the refId when the click_id could not travel.

For example, a Typeform embed receives the Click ID when the page loads (a destination), then returns the conversion on submit (a source).

Fields that carry the Click ID value

Each platform stores the Click ID value in its own field. These field names are not new identifiers. They hold the same Click ID value. For the end-to-end external-form → CRM workflow, see Pass the Click ID from External Forms to Your CRM.

Platform	Field	Naming
Typeform	at_click_id	Fixed by the integration
Unbounce	click_id	Fixed by the integration
Elementor	_atid	Fixed by the integration
Calendly	utm_term or sfid	Fixed by the integration
ClickFunnels	click_id	Fixed by the integration
LeadsHook	click_id	Fixed by the integration
GoHighLevel	_atid (custom field)	Fixed by the integration
HubSpot	AnyTrack Click ID (contact property)	Fixed by the integration
LeadByte	c3	Fixed by the integration
Generic HTML form	Any name you choose, carrying the --CLICK-ID-- token value	Free

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HubSpot

Map the AnyTrack Click ID value into the AnyTrack Click ID contact property as shown in the HubSpot integration guide. AnyTrack is renaming this property from “AnyTrack Client ID” to “AnyTrack Click ID” to match the value it stores; until the update reaches your account it may still appear as “AnyTrack Client ID” — it is the same field.

Ad platform identifiers

Identifiers AnyTrack collects

AnyTrack reads each ad platform click ID, plus the platform client-side identifiers when present (for example, the Meta fbp and fbc cookies and the Google Analytics client ID _ga). These belong to the ad platforms. They feed into the AnyTrack Click ID. They do not replace it.

Click ID	Network
gclid	Google Ads
gbraid	Google Ads — app-to-web on iOS, when gclid is unavailable
wbraid	Google Ads — web-to-web on iOS/Safari ITP, when gclid is unavailable
fbclid	Facebook Ads
ttclid	TikTok Ads
msclkid	Microsoft Ads
tblci	Taboola
ob_click_id	Outbrain

The identifier AnyTrack sends back

To raise Event Match Quality, AnyTrack sends the AnyTrack Client ID to each platform as that platform matching identifier through Conversion API:

Network	AnyTrack Client ID sent as
Facebook Ads	external_id
Google Ads	user_id
TikTok Ads	external_id

AnyTrack Identifiers FAQ

FAQ was last reviewed on 2026-06-30

What is the difference between the Client ID and the Click ID?

The Client ID (cid) is a cookie that identifies the visitor. The Click ID (click_id) identifies an action that visitor performed, and it is the value that travels between platforms. In server-side setups, the Click ID is the Property ID joined to the cid: {propertyid}{cid}.

What is the difference between atclid and click_id?

The atclid is the 30-character Click ID for the whole page session, generated once when the page loads. The click_id is 34 characters: it extends the atclid with 4 characters that identify a specific element, so each link, form, or cart gets its own value.

When does AnyTrack generate a Click ID server-side?

Whenever the Tracking Tag cannot run: Facebook Lead Ads, offline conversions, headless checkouts, and contacts created directly inside a CRM. Creating a contact in the HubSpot interface, for example, triggers the AnyTrack app for HubSpot to generate a server-side Client ID. See Server-Side Client ID.

When should I use refId instead of the click_id?

Use refId when the click_id cannot be passed to a destination such as a CRM. It aliases the visitor by an external value you control, like an email or your own customer ID, so later events identified by that value match back to the same visitor. See External ID as Click ID.

What identifier does AnyTrack send to Meta and Google for matching?

AnyTrack sends the AnyTrack Client ID to each ad platform as that platform matching identifier: external_id for Facebook Ads and TikTok Ads, and user_id for Google Ads. This raises Event Match Quality on conversions sent through Conversion API.

Do I need to set up these identifiers manually?

No. For standard integrations in the catalog, AnyTrack generates and passes the identifiers automatically. Manual work is only needed for custom platforms or advanced cross-platform setups.

AnyTrack Click ID

How the Click ID connects every touchpoint in the customer journey.

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Server-Side Client ID

Generate a Client ID and track conversions without the Tracking Tag.

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External ID as Click ID

Alias a visitor with refId when the Click ID cannot reach your CRM.

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Event Attributes

The customer, product, and transaction data attached to each Click ID.

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