Kartra Opt-in Form Listener for GTM: GA4, Enhanced Conversions and Meta CAPI

Why this listener exists

Kartra has no public JavaScript event for a completed opt-in, and most Kartra funnels redirect to the next step. That leaves page-view tracking, which counts refreshes and direct visits.

This listener watches the form’s own state, the confirmation it renders and the redirect window, so a lead counts once and carries the contact data your ad platforms need.

Most form tracking fires on a button click or a thank-you page view. Clicks count validation failures and repeat clicks. Thank-you page views count refreshes, back-button visits and bookmarked links. This listener watches what Kartra actually renders, so the event is much closer to a real lead.

How it detects a real submission

kartra_form_success fires on the first of these success paths:

• An inline confirmation render
• The form removed or replaced after submit
• A redirect, caught on pagehide inside the submit window
• A same-domain thank-you page, matched to recent stored form data

kartra_form_failed fires when Kartra renders a validation error after the visitor has interacted with the form.

Every event carries ec_detection_method, so you can segment reports by how each lead was detected and see which signals your site actually uses.

Install it in Google Tag Manager

1. Download the GTM tag above, or copy kartra-form-tracker.gtm.html from the GitHub repository.
2. In GTM, create a Custom HTML tag and paste the file in. It already includes the <script> wrapper.
3. Trigger it on All Pages (Page View), or on Consent Initialization if your consent setup needs the tracker available early.
4. Create a Custom Event trigger for kartra_form_success. Use the regex ^kartra_form_(success|failed)$ if you also want failures.
5. Create Data Layer Variables for the keys you need (table below), then attach your GA4, Google Ads, Meta or server-side GTM tags to the trigger.
6. Open Preview, submit a real test form and confirm kartra_form_success appears with the expected ec_detection_method. Then publish.

Retire any old click or thank-you page conversion for the same form, otherwise each lead is counted twice.

Events and dataLayer keys

Using it for Enhanced Conversions and Meta CAPI

• Google Ads Enhanced Conversions: map ec_email and ec_phone (or the _sha256 versions) into a User-Provided Data variable on your conversion tag.
• Meta Pixel and CAPI: send ec_event_id as the event ID on both the browser and server event so Meta counts the lead once.
• GA4: do not send raw ec_* PII or ec_raw_fields to GA4. Its terms prohibit PII in event parameters. Send form_id, form_platform and ec_detection_method instead.
• Duplicates: with dedupe: true (the default), a repeat success for the same form, email or phone within 5 minutes is suppressed.

Configuration and consent

Set window.EC_FORM_CONFIG before the tag loads to change the defaults:

window.EC_FORM_CONFIG = {
  debug: false,            // [EC] console logs, Preview only
  hashPii: false,          // add ec_email_sha256 / ec_phone_sha256
  dedupe: true,            // suppress repeat success within 5 min
  ttlMs: 600000,           // freshness window for thank-you recall
  defaultCountryCode: "1", // phone normalization fallback
  extraThankYouPatterns: [] // extra thank-you URL substrings
};

The tracker checks consent before it fires or writes storage. It auto-detects Google Consent Mode v2, OneTrust and Cookiebot. With analytics consent denied, nothing fires and nothing is stored. With PII consent denied, events still fire but email, phone, name and hashes are removed. Any other CMP can be wired in with window.EC_FORM_CONSENT_CHECK. If no CMP or override is found, the tracker assumes full consent, so match it to your own legal requirements.

Test it before you publish

• Submit a valid form. Expect one kartra_form_success.
• Submit with a required field empty. Expect kartra_form_failed and no success event.
• Fix the error and resubmit. Expect one success (recovery is allowed).
• Refresh the confirmation or thank-you page. Expect nothing new.
• If the page has two forms, submit each and check form_position and form_index.
• Run window._ecFormTrackers.kartra.status() in the console to see version, consent state, attached forms and the last event.

Troubleshooting

• No ec_tracker_initialized in Preview? The tag is not firing on that page, or consent for analytics is denied.
• Events in Preview but not live? Make sure the container is published, and that a cache or script optimizer (for example WP Rocket delay JS or Cloudflare Rocket Loader) is not deferring GTM.
• Set debug: true in EC_FORM_CONFIG to see [EC] logs while testing.

Known limitations

• pagehide is a fallback, not a perfect confirmation signal.
• A redirect to a different domain (for example a Kartra-hosted next step) cannot use same-domain recall.
• Kartra markup may change. Test on the live page before publishing.
• Bot or spam submissions that pass the platform’s own validation still count as success.
• Phone normalization is best-effort. The raw value stays in ec_raw_fields when PII consent allows it.

Changelog

• 3.0.1: first public standalone release. Confirmation-render detection, success and failure events, consent gate (Consent Mode v2, OneTrust, Cookiebot), PII redaction, optional SHA-256 hashing, 5-minute dedupe, ec_event_id, thank-you recall and the status() debug API.