Identifying visitors

11 min

Identifying a visitor means attaching known details, such as an email address, a name or a custom field, to the anonymous visitor in the current browser. Once identified, the visitor can be targeted with the Visitor fields filter and email-platform filters, greeted by name with Dynamic text (personalization variables), and synced to your integrations. If the email or phone matches a visitor Personizely already knows, for example from another device, the two profiles are merged.

Available on: all platforms. Shopify customer recognition needs the Shopify app; email-platform click IDs need the matching integration.

Ways to identify a visitor

Source	How it works	Needs
email= in the URL	A valid email in an email parameter on any page	Nothing
Email-platform click IDs	A subscriber ID your email platform adds to links	The email integration connected and enabled
Logged-in Shopify customers	The customer's account is read when they're logged in	Shopify
ply.identifyVisitor	Your code sends the fields	A developer
Widget forms	The visitor submits a form or survey in a widget	A form element
Parsers	Values are read from your page, cookies, storage or URL	Parsers set up in Settings → Parsers

All sources update the same visitor profile. Identification from the URL and from Shopify happens before targets are evaluated on that page, so the page already sees the identified profile. Forms, ply.identifyVisitor and parsers that find their value late update the profile during the page view; see How targeting works for what's re-checked then.

Email in the URL

Add email= with the subscriber's address to any link to your site:

https://example.com/collections/new?email=jane%40example.com

The parameter name is exactly email (lowercase), and the value must be a valid email address. URL-encode the @ as %40 if your email platform doesn't do it for you; both forms work.

It works on any page, alongside other parameters such as UTMs.

Most email platforms can insert the subscriber's email with a merge tag, for example ?email={{ email }} in Klaviyo or ?email=*|EMAIL|* in Mailchimp.

An email in a URL ends up in browser history, server logs and analytics tools. Use an email-platform click ID instead where your platform supports it, and check your privacy policy before putting emails in links.

Email-platform click IDs

When one of these integrations is connected and enabled, a link that carries the platform's subscriber ID identifies the visitor. Personizely looks the contact up in your email platform, links the visitor to it and copies the contact's details, such as email and name, into the profile.

Platform	URL parameter
ActiveCampaign	ac_cid
AWeber	aw_cid
Brevo (Sendinblue)	sib_cid
CleverReach	crcustomer
Constant Contact	cc_cid
ConvertKit (Kit)	ck_subscriber_id
Dotdigital	dd_cid
GetResponse	gr_cid
HubSpot	hs_cid
Hyperise	utm_hyperef
iContact	ic_cid
Klaviyo	kl_pid
Mailchimp	mc_eid
MailerLite	ml_cid
Mailjet	mj_cid
Moosend	moo_sid
Omnisend	omnisendContactID
Ometria	om_profile
Ontraport	on_cid
Sender	se_cid
SendGrid	sg_cid
Sendlane	sl_cid
SendPulse	sp_cid
SmartrMail	sm_cid

The value must be the contact's ID in that platform. Some platforms add it to links automatically; for the others, add the parameter to your email links with the platform's merge tag for the contact ID. If the integration isn't enabled, the parameter is ignored.

Logged-in Shopify customers

When a customer is logged in to their Shopify account, Personizely identifies the visitor as that customer once per session. The customer's email, first name, last name and phone are copied from Shopify into the profile, and the visitor is linked to any existing profile with the same email.

The Customer filter (Shopify) and Order history filter filters also read the logged-in customer's account directly, so they work on the first page after login.

ply.identifyVisitor

Send profile fields from your own code, for example on a custom site with its own login:

window.plyLayer = window.plyLayer || [];
window.plyLayer.push(['identifyVisitor', {
  email: '[email protected]',
  firstName: 'Jane',
  customFieldValues: { '42': 'wholesale' }
}]);

It accepts every Visitor fields reference that a form can collect, plus customFieldValues keyed by Custom fields ID. Unknown fields are ignored. Full parameter reference: JavaScript API.

When a visitor submits a Form element or Survey element in a widget, the values of its fields are saved to their profile: default fields such as email and phone, and any custom fields the form uses. The submission also appears in Contacts and form submissions.

Parsers

A Parsers (data parsing engine) with the Visitor destination reads a value from your page (a JavaScript variable, cookie, local storage key, URL parameter or element) and saves it to a profile field. Use it to identify customers when your platform already exposes their email or ID on the page and you can't add code.

How profiles merge

When a source sets an email or phone that already belongs to another visitor profile on your website, Personizely merges the two:

The current, usually anonymous, visitor is merged into the existing profile. The existing profile receives the newly submitted fields.

The anonymous visitor's history (page views, events, goal hits, widget and campaign activity) is moved to the existing profile shortly afterwards, and the anonymous profile is removed.

The browser is linked to the existing profile from then on.

Email-platform click IDs merge the same way: a visitor already linked to that contact is reused, and otherwise the contact's email decides which profile to use.

Before	After identifying with [email protected]
Laptop: known visitor with email [email protected], 3 orders	Unchanged
Phone: anonymous visitor, 5 page views	Merged into the laptop profile: one profile with both histories

What merging doesn't do:

It doesn't merge campaign assignments. Each browser keeps the A/B test arms it was assigned. The phone can be in a different arm from the laptop. See How visitors are assigned to variations.

It doesn't change the other browser. The laptop keeps its own cookie and session.

It doesn't happen on name or custom fields. Only email and phone (and email-platform contact IDs) identify the same person.

Behavior details and limitations

Later values overwrite earlier ones. If a visitor submits a form with a new first name, the profile's first name changes.

Anonymous visitors have empty fields. Visitor fields filters and {visitor.*} dynamic text only have values after identification. Use a fallback in dynamic text, for example {visitor.firstName or 'there'}.

Identification can change targeting results. After merging into a profile with an earlier first visit, "First visit is now" becomes false and history filters include the merged history.

Phone numbers without a country code are converted to international format using the visitor's country.

Consent fields are just fields. Setting emailMarketingConsent records the visitor's consent in Personizely and passes it to integrations; it doesn't change how the snippet stores data. See Cookies and consent.

Examples

Klaviyo campaign links: with the Klaviyo integration enabled, links carrying kl_pid identify subscribers. Target "Visitor fields: Email is not empty" to hide the newsletter popup from them.

Personal greeting: a personalization headline "Welcome back, {visitor.firstName or 'friend'}" for visitors who arrive from an email.

Custom login: a membership site pushes identifyVisitor with the member's email and a custom field "Plan", then targets a renewal widget at "Plan is Annual".

Troubleshooting

Visitor isn't identified from the link → the email isn't valid, the parameter name isn't exactly email, or the click-ID integration isn't enabled. Check the console with ?ply_debug=1.

Fields appear on the next page, not this one → the value came from a form, identifyVisitor or a late parser. Campaigns that already ran on this page aren't re-run with the new data in every case; widgets re-check when their trigger fires.