GTM Template – GA4 Client & Session ID with readAnalyticsStorage

This repository provides a Google Tag Manager (GTM) custom template that uses the new readAnalyticsStorage API to reliably access Google Analytics 4 (GA4) Client ID and Session ID.

Usage :

Import the .tpl file into GTM under Templates → Variable Templates.

Create a new variable based on this template.

Choose whether to return the Client ID, the Session ID, or both.

Optionally, store values in cookies or localStorage for later use.

Why use it?

Official, stable API from Google (no more fragile regex hacks on the _ga cookie).

Reliable and secure way to access GA4 identifiers.

Useful for advanced tracking and user journey analysis.