Track Scroll Depth, Outbound Clicks & Downloads with GTM

Pageviews tell you someone arrived; engagement events tell you whether they actually did anything.Scroll depth, outbound link clicks and file downloads are three of the easiest, highest-value engagement signals to add, and GTM has built-in triggers for all of them. Here's how to set each up cleanly.

Scroll depth tracking

Scroll depth shows how far down a page people actually read, invaluable for long content, landing pages and articles. GTM has a built-in Scroll Depth trigger, so no code needed.

1. Enable the built-in Scroll Depth variables (Scroll Depth Threshold, etc.).
2. Create a Scroll Depth trigger with vertical percentages 25, 50, 75, 100.
3. Fire a GA4 event (e.g. scroll) with the threshold as a parameter.

Outbound link clicks

Outbound clicks (links to other sites, affiliate links, partner sites) show where you're sending traffic. Use the built-in Just Links click trigger with a condition on the link URL.

1. Enable the built-in Click variables (Click URL, etc.).
2. Create a Just Links trigger that fires when Click URL does not contain your own domain.
3. Fire a GA4 event (click with outbound: true) and pass the Click URL.
4. Tick Wait for Tags so the hit sends before the browser navigates away.

File downloads

Same mechanism, different condition. Fire a Just Links trigger when the Click URL ends in a file extension you care about (pdf, zip, xlsx), and send a GA4 file_download event with the file URL.

Gotchas

• Navigation races the hit. For outbound clicks and downloads, use Wait for Tags (and rely on GA4's sendBeacon) so the event isn't cancelled.
• Subdomains. Make your "own domain" condition account for subdomains so internal links aren't logged as outbound.
• GA4 already has some of this. Enhanced Measurement covers scroll (90%), outbound clicks and file downloads automatically, check what you already get before duplicating it.