What AI engines we track

We measure brand visibility across up to five AI surfaces that together account for the lion's share of AI-mediated discovery traffic in 2026. Each one returns a different kind of answer, with different citation behaviour, so we treat them as separate signals and combine them at the end.

Which engines run depends on your plan — every plan from Free up adds more coverage:

Plan	Engines measured
Free	Perplexity
Starter	ChatGPT + Perplexity
Pro	ChatGPT + Perplexity + Google AI Mode + Gemini
Business / Scale	ChatGPT + Perplexity + Google AI Mode + Gemini + Google AI Overview

The two Google surfaces are different engines and we measure them separately: Google AI Mode is the dedicated AI tab on google.com, and Google AI Overview is the AI panel that appears above the classic search results. See Google AI Mode for the full distinction.

The engines

ChatGPT (OpenAI)

The largest AI-search audience by daily active users. ChatGPT answers tend to be longer and more discursive than Perplexity, and citations are optional — the model decides when to surface a source. We capture the real ChatGPT answer for each query through a stable, production-grade pipeline — the same answer a fresh user with search on would get — rather than reconstructing it from a raw model call.

Default weight in the GEO Score: 0.35.

Perplexity (Sonar)

Built for retrieval — every answer comes with an explicit list of citations and excerpts. Perplexity tends to attribute claims more rigidly than ChatGPT, which is why it's a great signal for "is the brand actually backed by web evidence?". We use Perplexity's official Sonar API.

Default weight in the GEO Score: 0.15.

Google AI Mode (Pro and up)

The dedicated AI tab on google.com — Google's own conversational search surface, distinct from the AI Overview panel above the organic SERP. Google AI Mode reaches roughly 1.5 billion users per month, which is why it carries a heavy weight despite being a younger surface. We capture Google's own real AI Mode answer for each query through a stable, production-grade pipeline — the same answer a fresh user would get — without crawling google.com ourselves. See the dedicated Google AI Mode article for details.

Gemini (Pro and up)

Google's standalone Gemini assistant — a separate answer surface from the two google.com search experiences above. We capture Gemini's real response for each tracked question so you can see how Google's flagship model talks about your brand, independent of how its Search products do.

Google AI Overview (Business and Scale)

The AI panel Google renders above the classic search results for some queries — different from the AI Mode tab. Google decides when to show it, so an absent panel is itself a meaningful visibility signal: we record it as a real "no AI Overview rendered" result rather than a failure. We capture the actual panel Google returns for your query.

How they compare side by side

Property	ChatGPT	Perplexity	Google AI Mode	Gemini	Google AI Overview
Citation density	Optional	High (numbered)	High (inline)	Medium	High (inline)
Average answer length	Long, discursive	Medium, structured	Long with tables	Medium, conversational	Short, summary
Tone	Conversational	Reference-like	Encyclopedic	Conversational	Summary panel
Best signal it gives	"How AI tells the story of your brand"	"Who's actually cited as a source"	"What Google's own search LLM thinks"	"What Google's flagship model thinks"	"What Google surfaces above the SERP"
Mention extraction	LLM-classified	Engine-native references	Engine-native references	LLM-classified	Engine-native references

Why these engines

The engines above cover where the great majority of B2B buyer-discovery traffic actually flows in 2026. We deliberately don't yet track Claude, Grok, or Meta AI — they're either niche audiences for B2B buyers or have no public answer surface we can capture reliably. Adding more engines before they earn it would dilute the score with noisy signals.

When we do extend, our priority order is Claude search (when it ships a public retrieval mode), then Meta AI (if it gets a citation surface that isn't behind a Facebook wall). We re-evaluate this every quarter.

What we don't claim

Where the math lives

The per-engine effective rate is computed exactly the same way for each engine — see the GEO Score article — and the combined score is a weight-normalised average across whichever engines returned data.

Before any engine cites you, the bot has to fetch you

Each engine runs its own crawler — OAI-SearchBot for ChatGPT, Claude-Web for Claude.ai, PerplexityBot for Perplexity, and Googlebot plus the Google-Extended opt-out for Google AI Mode. Your robots.txt and HTTP headers decide whether they can fetch your site in the first place. See How AI bots discover your site for the bot taxonomy, and the AI Crawlability Monitor for the audit that catches accidental blocks.