How HubSpot UTK Works with Vector

Last updated: September 15, 2026

Overview

HubSpot assigns a unique visitor ID, called a UTK, to site visitors to help track their activity. When the Vector Pixel is installed alongside HubSpot tracking, Vector can read this UTK and use it to match a site visitor to an existing contact record in HubSpot.

This helps Vector connect site activity with known HubSpot contacts and accurately sync activity back to the correct contact record.

How the Flow Works

1. HubSpot Creates a Visitor ID (UTK)

When someone visits a page with HubSpot tracking installed:

  • HubSpot automatically assigns a unique ID (UTK) to the visitor.

  • The UTK is stored in the visitor's browser.

  • HubSpot uses the UTK to associate site activity with that visitor.

2. The Vector Pixel Reads the UTK

When the Vector Pixel is active on the same website:

  • The Vector Pixel loads alongside the HubSpot tracking script.

  • Vector looks for the UTK stored in the visitor's browser.

  • If found, Vector includes the UTK when sending site activity to Vector.

3. Vector Matches the Site Visitor

Once Vector receives the UTK:

  • Vector uses the UTK to check whether HubSpot has an existing contact associated with that visitor.

  • If HubSpot has a matching contact, Vector can associate the site activity with available contact information, such as:

    • Email address

    • Name

    • Company

    • Other available contact metadata

This allows Vector to associate the site visitor and their activity with the appropriate known contact.

4. Vector Stores and Uses the UTK

After a match is made:

  • Vector stores the UTK and associated contact data.

  • When syncing activity back into HubSpot, Vector can use the stored information to match the site visitor to the appropriate HubSpot contact record.

  • This helps ensure activity is associated with the correct person without creating unnecessary duplicate records.

Visual Flow

Site visitor visits your website
        ↓
HubSpot creates a UTK and stores it in the browser
        ↓
Vector Pixel reads the UTK
        ↓
Vector sends the UTK to Vector
        ↓
Vector checks HubSpot for a matching contact
        ↓
HubSpot returns available contact information (if matched)
        ↓
Vector associates the UTK with the contact and site activity
        ↓
Vector uses the match when syncing activity back to HubSpot

What Vector Can Do with UTK

Vector can use HubSpot UTKs to:

  • Identify existing HubSpot contacts when a UTK can be matched to a known record.

  • Associate site visitors with known contacts when HubSpot has a corresponding contact.

  • Connect site activity to the appropriate contact in Vector.

  • Use the match when syncing activity back to HubSpot.

What Vector Cannot Do with UTK

Vector cannot assign a HubSpot UTK to a new contact created in HubSpot.

HubSpot controls UTK creation and assignment. UTKs are generated through HubSpot's own website tracking and must originate from HubSpot rather than Vector or another external system.

This helps prevent:

  • Duplicate UTKs

  • Incorrect associations between site activity and contacts

  • Inaccurate attribution or visitor tracking

Because of this, Vector can read and use an existing HubSpot UTK, but it cannot create or assign one on HubSpot's behalf.

Quick Recap

When HubSpot and the Vector Pixel are both active on your site:

  1. HubSpot assigns a UTK to the site visitor.

  2. The Vector Pixel reads the available UTK.

  3. Vector uses it to look for a matching HubSpot contact.

  4. When a match exists, Vector can associate the site activity with that contact.

  5. Vector can use that association when syncing activity back to HubSpot.

The UTK itself always originates from HubSpot. Vector uses the existing identifier to help connect site activity with the correct contact record.