Developing
A small change that gives teams an allowlist instead of a growing list of exclusions.
In 60 seconds
- On September 21, 2026 Google Analytics added support for "Include" data filters on hostnames.
- Teams can define a list of approved hostnames for event data collection.
- Events with empty hostnames, which typically signal spam or abnormal traffic, are blocked automatically.
- Hostname filters do not affect data sent through the Measurement Protocol.
Impact Layer
- What changed
- Teams can now permit known hostnames instead of excluding bad ones one by one.
- Why it matters
- Spam and ghost traffic distort conversion rates and campaign reports, and an allowlist is easier to maintain than a blocklist.
- Who is affected
- Analysts and web teams that run GA4 on one or several domains.
- Martech stack area
- Analytics
- Stack impact
- List every domain and subdomain that should send data before turning the filter on, including checkout and app domains.
- Business impact
- Low Taken from Google's release-notes page. A mistake in the list will drop real data.
- Related technologies
- What to watch
- Whether Google extends filters to the Measurement Protocol.
Google’s release notes for Google Analytics list a data-quality feature dated September 21, 2026: support for “Include” data filters on hostnames.
What it does
- Organisations can define a list of approved hostnames for event data collection, an allowlist approach rather than manual exclusions.
- The system automatically blocks events with empty hostnames, which typically signal spam or abnormal traffic.
- The Measurement Protocol is not affected by hostname filters, so data sent that way continues to flow.
Our read
Ghost traffic from fake hostnames inflates sessions and drags down conversion rates, and many teams keep a growing list of exclusions. An allowlist reverses the burden: only domains you name count. That is simpler, with one risk. If you forget a subdomain, a checkout or a regional site, its data disappears from reports. List every domain that should send data, test the filter on a duplicate property first, and remember that server-side events sent through the Measurement Protocol bypass it.
Sources
- Google Analytics Help: What's new in Google Analytics (opens in a new tab)
Source of the hostname filter entry and the September 29 app-conversion entry.