Every UTM parameter and every AI-referral signature you will see in GA4, in one reference. UTM parameters tag where a visit came from; utm_source and utm_medium are required for GA4 to classify it. AI tools like ChatGPT (utm_source=chatgpt.com) and Claude (claude.ai/referral) append their own referrer when they cite you and a user clicks through.
Standard UTM parameters
UTM parameters are tags you add to a URL so analytics knows where a visit came from. Two are required for GA4 to classify the session correctly; the rest add detail.
| Parameter | What it records | Example | Required? |
|---|---|---|---|
utm_source | The origin (site or engine) | google, chatgpt.com, newsletter | Yes |
utm_medium | The channel type | cpc, email, referral, social | Yes |
utm_campaign | The campaign name | spring_sale_2026 | Recommended |
utm_term | The paid keyword | ai seo consultant | Optional (paid) |
utm_content | Which link or ad was clicked | header_cta vs footer_cta | Optional |
utm_id | Campaign ID (GA4) | abc123 | Optional |
AI referral signatures in GA4
AI tools append their own referrer when they cite you and a user clicks through. These are not UTMs you set; they are how the visit shows up. Group them into one AI channel.
| Signature | Tool | Shows in GA4 as | Means |
|---|---|---|---|
utm_source=chatgpt.com | ChatGPT | Referral / chatgpt.com | ChatGPT cited you and the user clicked |
claude.ai/referral/[date] | Claude | Referral (date-fragmented) | Claude cited your page |
perplexity.ai | Perplexity | Referral | Perplexity cited your page |
copilot.microsoft.com | Microsoft Copilot | Referral | Copilot cited your page |
gemini.google.com | Gemini | Referral | Gemini cited your page |
| Google AI Mode | Usually organic or direct | Hard to isolate from normal Google |
A meaningful share of AI traffic also lands as direct, because users copy and paste the URL rather than click. Build one GA4 channel grouping all AI sources, then measure it together. See how to measure AI search traffic and utm_source=chatgpt.com explained.
Frequently asked questions
Which UTM parameter records the ad a user clicked on?
utm_content is the parameter that distinguishes which specific ad or link was clicked, for example two ads pointing to the same page. utm_term records the paid keyword. utm_source, utm_medium and utm_campaign capture the origin, channel and campaign.
What does utm_source=chatgpt.com mean?
It means ChatGPT cited your page as a source and the user clicked the link. It appears as referral traffic in GA4 and is the main way to attribute ChatGPT referral visits.
What is claude.ai/referral in my analytics?
It is Claude's referrer signature, appended when Claude cites your page and a user clicks. The date suffix is the conversation date, not a campaign; group all the date rows into one Claude channel.
Are utm_source and utm_medium required?
Yes. GA4 needs both to classify a session into a channel. Without them a tagged visit may fall into unassigned or direct.
Soaring Above Search
Weekly AI search insights from the front line. One newsletter. Six sections. Everything that actually moved this week, with a practitioner's take.
Chief of Staff at StudioHawk, Australia's largest dedicated SEO agency. Specialising in AI search visibility, technical SEO, and organic growth strategy. Leading a team of 120+ across Melbourne, Sydney, London, and the US. Book a free consultation →