The GA4 conversion reporting/tracking is causing significant issues.
I’ve set up cross-domain tracking streams, and when I test conversion tracking via debug mode, every conversion is recorded.
However, outside of testing, only 1 or 2 conversions are tracked monthly. Meanwhile, I’m observing numerous conversions in HubSpot CRM.
I’d appreciate any insights or assistance in resolving this discrepancy.
The short answer is:
The significant conversion discrepancy between Google Analytics 4 (GA4) and your HubSpot CRM is a common result of client-side tracking limitations, primarily caused by browser restrictions, ad-blockers, and consent management platforms which prevent the GA4 tag from firing reliably.
The technical and actionable solution is to implement server-side conversion tracking by leveraging the HubSpot API and the Google Analytics Measurement Protocol.
You should configure a HubSpot webhook to trigger on a confirmed conversion event in the CRM, sending the conversion data along with the client-side identifiers (like the client_id and session_id captured via Google Tag Manager and stored in a hidden field or custom property) to a server-side environment like Stape or Google Cloud Platform (GCP).
The server environment, running server-side GTM, will then use the Measurement Protocol to dispatch the conversion event directly to GA4’s servers.
This server-to-server approach bypasses browser-side issues, ensuring that a confirmed conversion in HubSpot is always recorded in GA4, which is significantly more cost-effective than relying on unreliable client-side data.
The long answer is:
Your current low GA4 conversion count, despite high numbers in the HubSpot CRM, strongly indicates a deficiency in your client-side tracking setup, where the GA4 tag is failing to execute for a large percentage of your converting users due to factors outside your control like aggressive browser-level privacy controls, ad-blocking software, or user-initiated cookie consent denials.
The fix is to shift the responsibility for conversion reporting from the unreliable user’s browser to your own server environment through an API-based integration.
This process begins by using the HubSpot API, specifically its webhook or contact/deal engagement functionality, to detect when a conversion reaches a confirmed state in your CRM, such as a contact creation or a deal stage change.
When this event occurs, the HubSpot API is utilized to send a payload of critical data to a cloud-based server-side tagging environment, which can be hosted cost-effectively on a service like Stape or on a managed service like GCP’s Cloud Run or App Engine.
Crucially, your client-side GTM setup must be updated to capture the user’s Google Analytics Client ID and Session ID and pass these identifiers to HubSpot alongside the conversion data, likely using hidden form fields or custom contact properties, as these are mandatory for GA4 to correctly attribute the server-side conversion back to the original session and traffic source.
Once the server receives the confirmed conversion data, the server-side GTM instance processes it and uses the Google Analytics Measurement Protocol to construct and send a secure HTTP request directly to the GA4 servers.
This direct server-to-server communication is impervious to the client-side barriers that are currently suppressing your conversion counts, providing a robust, highly accurate, and privacy-compliant mechanism for reconciling the data between your authoritative CRM and your primary web analytics platform.
Furthermore, to provide even deeper reporting and to join this rich, confirmed conversion data with your existing web data, you could also leverage the Google Analytics Data API to build custom reports in a tool like Looker Studio, thereby combining the fidelity of your HubSpot data with the attribution power of GA4 for superior marketing optimization.
This server-side integration is a long-term, cost-effective solution as it future-proofs your tracking against continuous browser privacy updates and ensures the integrity of your marketing budget decisions.
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