setUserId()

wf.setUserId(userDomain, userId)

Identify a visitor with a known user ID. This client-side API tells Webflow who the visitor is so that off-site conversions can be attributed to their session.

Syntax

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wf.setUserId(userDomain: string, userId: string): void

Parameters

• userDomain (required): string — A label identifying the system where your user data lives (e.g., salesforce, marketo, applicationId). This helps distinguish between different ID sources.

• userId (required): string — The unique identifier for the user in your system. This must match the userId you send in the server-side API request.

Example

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wf.ready(function() {
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    wf.setUserId('salesforce', '72349876');
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});

When to call setUserId

Call wf.setUserId() as soon as you know the visitor’s identity. Common scenarios include:

• After a user logs in
• When a user submits a form with identifying information
• When you can match the visitor to a record in your CRM or database

The user ID must be set before the visitor leaves your site. Once set, Webflow can attribute any subsequent off-site conversions to this visitor’s session. The user ID persists for the duration of the session, which ends after 30 minutes of inactivity or a 24-hour maximum timeout.

Choosing a user ID

The value you use for the ID depends on the system where your user data lives. Common sources include:

• In-house databases
• Salesforce contact IDs
• Marketo lead IDs
• Application or account IDs

Choose an ID that’s available on both the client side (your website) and server side (your backend systems) so you can match conversions correctly.

Example: Credit card application

In this example, a visitor fills out a form to apply for a credit card. The actual conversion (approval) happens later, after a review process.

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wf.ready(function() {
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    // Use the application ID as the user identifier
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    wf.setUserId('applicationId', '123456789');
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});

Later, when the application is approved, your backend sends the conversion event using the same userDomain and userId via the server-side API.

Returns

This method doesn’t return a value. The user ID is stored and associated with the visitor’s session.

FAQs