AI traffic blind spot
GA4 now has a native AI Assistants channel, and it covers 5 platforms. It does not cover everything, and the gaps land in channels you already report on as something else.
Below is the exact custom channel group configuration that closes the referrer-shaped part of that gap, and a straight account of the part no configuration closes.
Optional, and honest about what it does: the configuration below is identical for every property. Adding a domain only labels this page so you can send the link to that client and have it read as theirs. Nothing is stored.
chatgpt\.com|chat\.openai\.com|perplexity\.ai|gemini\.google\.com|claude\.ai|copilot\.microsoft\.com|deepseek\.com|grok\.com|you\.comGA4 matches regular expressions with RE2, where an unescaped . matches any character — so chatgpt.com would also match chatgptXcom. Every dot above is escaped. Paste it exactly as it is.
8 platforms, 9 hostnames. Includes the platforms GA4 already covers natively, deliberately: matching them yourself costs nothing and catches sessions from before the native channel existed.
Setting it up
Open Admin
In the GA4 property you're reporting on, click the gear icon in the bottom-left.
Go to Data display → Channel groups
You'll see the read-only Default channel group. You cannot edit it — that's why this is a custom group.
Create a new channel group
Click “Create new channel group”. Name it something a client will understand in a report: “AI search” works.
Add a channel with Source matches regex
Click “Add new channel”, name the channel “AI assistants”, then set the condition to Source · matches regex and paste the expression above.
Order it above Referral
Drag the new channel above Referral. Channel groups evaluate top-down and first match wins — below Referral, every one of these sessions is swallowed as a generic referral and your channel stays empty.
Save, then give it 24–48 hours
Custom channel groups apply to reporting going forward and reprocess a limited window of history. Don't judge it on the first afternoon.
What GA4’s native channel misses
None of these are bugs. They follow from how referrers work and how Google scoped the channel. They matter because each one lands somewhere you already report on, under a label that says something else.
| What | Where it actually lands | Why |
|---|---|---|
| Perplexity | Referral | Not in Google's native channel list |
| Google AI Overviews | Organic Search | Keeps a google.com/search referrer |
| Google AI Mode | Organic Search | Same |
| No-referrer AI visits | Direct | Browser or app strips the referrer |
| Sessions from before the channel shipped | Unclassified | The channel is not retroactive |
A substantial share of AI referral sessions carry no referrer at all. No referrer-based method — including this one — sees those. They are in Direct, indistinguishable from someone typing the URL. Set this up because it recovers the part that is recoverable, and tell your client that it is a floor on AI traffic, not a measurement of it.
Where these 8 platforms came fromChecked 2026-08-10
Read from Google’s default channel group documentation on 2026-08-10. The list has been reported inconsistently elsewhere, so here is exactly what that page says:
- Google's live documentation names five platforms by example: "users arrive at your site from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok."
- The rule is medium-based, not source-based: "The medium exactly matches 'ai-assistant'." Google sets medium to `ai-assistant` and campaign to `(ai-assistant)` when the referrer matches its own list.
- Google does not publish the referrer list behind that rule — it is proprietary. No list, including this one, can be called exhaustive.
- Google explicitly excludes "Google's AI Overviews and AI Mode" from the AI Assistants channel.
- Perplexity is absent from Google's named list — it still lands in Referral. This is the single most consequential gap for SEO reporting.
- Claude's status is contested across sources: the launch announcement reportedly named Claude, the live documentation's example list does not. We treat it as not covered, which is the safe direction — see `nativeChannel: 'contested'`.
- Google's documentation gives no effective date for the AI Assistants channel. Secondary sources place the launch in May 2026. We therefore do NOT print a specific cutoff date as fact; see `retroactivity`.
Not covered natively: Perplexity, Claude (contested), You.com. This page fails its own build if that check goes more than 90 days without being redone.
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