Understand Klaviyo's anonymous visitor activity backfill

You will learn

Learn about anonymous visitor activity backfilling and how to capture shoppers’ onsite engagements before they are identified.

Before you begin

By default, Klaviyo’s web tracking supports:

• Active on Site tracking
  This metric is tracked whenever an identifiable browser visits your website.

• Viewed Product tracking
  This metric is tracked whenever an identifiable browser views a product page on your website (for ecommerce stores).

Active on Site can help segment your contacts based on engagement level, while Viewed Product tracking can enable you to send customers reminders in a browse abandonment flow. 

Klaviyo’s standard web tracking

In order for Klaviyo to track a shopper’s onsite activity by default, they must be identified. This is done through Klaviyo’s JavaScript, which sets a cookie that allows for the tracking and identification of site visitors through an auto-generated ID when they:

• Fill out a Klaviyo signup form 
• Click a link from a Klaviyo email 

This cookie can temporarily hold personally identifiable information and lasts for two years.

Anonymous visitor activity backfill

With Klaviyo’s anonymous visitor activity backfill, you can capture onsite activity for a shopper prior to identification. Once that visitor is identified in the future, you’ll then have access to their historical onsite events. This allows you to have a more complete view of your customers’ journeys, regardless of when they are identified through Klaviyo’s web tracking. 

How Klaviyo collects onsite data for anonymous visitors

To collect onsite data for anonymous visitors, Klaviyo records data about a visitors actions as they occur and stores that locally in their browser. In the future when that visitor is identified, that data is then sent to Klaviyo and cleared from the browser. Any future onsite activity will be tracked as usual through the Klaviyo cookie once they have been identified as well. 

To store data in the browser, the shopper’s browser must support setting items in local storage.

Note that if a site visitor is using any type of cookie-blocking (e.g, incognito in Chrome or private browing in Safari) Klaviyo cannot record and recover anonymous events.

Disable anonymous visitor activity backfill 

If you have Klaviyo.js installed, anonymous visitor activity backfill is enabled by default. If you wish to disable the feature for your account:

To enable anonymous visitor activity backfill:

1. Navigate to Account > Settings in the bottom left corner in Klaviyo.
2. On the Data tab in your account settings, uncheck the Enable anonymous visitor tracking box.
3. Select the Update button.

Testing anonymous activity capture

To verify that anonymous visitor historical backfill is working, you can take the following steps: 

1. Navigate to your website in a private window and take an onsite action like Viewed Product.
2. Open the developer console on your browser and navigate to local storage. This may be on the developer console’s Storage or Application tab depending on your browser.
   
3. Verify that the key and values set in the browser match the actions you took while anonymous. Note the timestamp of the data. 
4. After confirming that data is being stored in the browser, add ?utm_email=example@gmail.com to the end of your website URL, replacing example@gmail.com with a test email address and reload the page. This will identify the browser based on the email address you provide.
5. Search for the email address in Klaviyo.

You should see a profile matching the email address that you supplied, with an activity timeline corresponding to the actions you took while anonymous. Ensure that the key and values in your local storage have been cleared out, and that the events have made their way into your Klaviyo account with the correct timestamps. 

Checkout web pixel

In addition to Klaviyo’s identification methods as part of standard web tracking, the checkout web pixel enables identification during checkout if customers submit their information.

Shopify

For a visitor’s identity to be captured during checkout, they must complete one of the following Shopify events:

• checkout_completed
• payment_info_submitted
• checkout_contact_info_submitted
• checkout_shipping_info_submitted

This will cause anonymous activity to sync over to the associated profile, even if they never submitted a Klaviyo form or clicked a link in a Klaviyo email or SMS.

In order for visitors’ identities to be captured during checkout, the following requirements must be met:

1. Anonymous activity tracking must be enabled.
2. Shopify behavioral events must be enabled.
3. Site visitors must accept marketing and analytics cookies.

WooCommerce

For a visitor's identity to be captured at checkout, they must submit their information and provide consent. Additionally, the following requirements must be met:

1. Anonymous activity tracking must be enabled.
2. Site visitors must accept marketing and analytics cookies.

This will cause anonymous activity to sync over to the associated profile, even if they never submitted a Klaviyo form or clicked a link in a Klaviyo email or SMS. 

Frequently asked questions

Is this feature enabled by default?

No, anonymous visitor activity backfill is not enabled by default. The feature must be toggled on in your account settings.  

What events are included in post-identification syncing? 

Only client-side events, also known as front-end events, are captured through Klaviyo’s web tracking for both identified and anonymous visitors. These events are captured through Klaviyo's main onsite tracking snippet, known as Klaviyo.js.

Some common events include:

• Active on site
• Viewed product
• Added to cart (if installed) 

However, any events recorded onsite via klaviyo.track() are also included in anonymous activity backfill. 

How many events can be stored in local storage?

There is a 5MB limit imposed by a browser’s local storage, allowing for up to 10,000 events. 

Why use local storage for data storage over cookies?

Cookies are less robust compared to local storage. For example, cookies have an expiration date and a maximum size of about 4KB. Local storage can hold 5 MB on average (depending on the browser).

Are there any GDPR or privacy concerns? 

Anonymous visitor activity backfill uses a browser's local storage to store data sent as a profile property or event until the browser is identified (after which the local data is cleared). 

Until it is cleared, data in local storage is accessible to any on-website Javascript. This can pose a privacy concern if you send certain types of sensitive data through front-end events. For sensitive data, Klaviyo recommends only sending the data via server-side requests, or only after a browser is identified.

Does anonymous visitor activity backfill work with a cookie consent tool?

If your store uses a cookie consent tool (e.g., OneTrust), the shopper would need to opt-in for anonymous activity to be captured. Without access, Klaviyo will not be able to write data to the browser’s local storage. 

Do anonymous visitors trigger flows?

Once an anonymous visitor is identified through Klaviyo's standard web tracking, they will trigger flows as long as they qualify and have not exceeded time delays. 

Additional resources 

• Getting started with Klaviyo onsite tracking
• Troubleshooting viewed product tracking
• Understanding cookies in Klaviyo