ChatGPT vs Gemini vs Perplexity: why a client's AI visibility differs by engine

It's common to see a client mentioned in most Perplexity answers, some Gemini answers and almost no ChatGPT answers — for the same questions, in the same week. That isn't a measurement error. The three engines find information differently, cite differently and lean on different sources. Track and report each engine separately, or an average will hide the problem you need to fix.

How each engine builds an answer

Two consequences follow. First, different sources produce different recommendations: a brand that's well covered on sites Google ranks highly can do well in Gemini and poorly elsewhere. Second, some answers come from the model's training data, not a live search — especially in ChatGPT for general questions — so recent changes on the web show up unevenly.

ChatGPT

ChatGPT decides whether a question needs a web search. For "best X in [city]" questions it usually searches; for broad category questions it may answer from what the model already knows. When it searches, OpenAI's crawler (OAI-SearchBot) is what lets a site appear in those results.

What to check for a client:

• Crawler access. If the client's robots.txt blocks OAI-SearchBot, OpenAI says its content won't be used in ChatGPT's search answers. (Blocking GPTBot, the training crawler, is a separate decision.)
• Referrals. ChatGPT adds utm_source=chatgpt.com to its links, so visits are visible in analytics.
• The full tracking method is in how to track brand mentions in ChatGPT.
• Training-data presence. For answers given without search, long-standing coverage — Wikipedia, major publications, well-known review sites — matters more than last month's blog post.

Gemini

Gemini can ground its answers in Google Search. When it does, Google's index and ranking shape which pages it reads, so classic SEO strength tends to carry over more directly than elsewhere.

What to check for a client:

• Google indexing and rankings for the pages that answer the prompt.
• Structured, quotable facts — prices, locations, specifications — on pages Google already ranks.
• Don't confuse Gemini with AI Overviews or AI Mode. They're related Google products, but the Gemini assistant, AI Overviews in search results and AI Mode are different surfaces and can give different answers. Know which one your tool measures.

Perplexity

Perplexity searches for virtually every question and cites its sources with numbered references. That makes it the most transparent engine to analyse: you can see exactly which pages led to a recommendation.

What to check for a client:

• Which domains get cited for the client's questions — directories, reviews, comparison articles, forums.
• Whether the client's own pages answer the exact question. Perplexity often cites the page that matches the question most directly.
• Freshness. Because it searches live, changes on the web can show up faster than in other engines.

Reporting by engine

Keep the overall numbers, but always add an engine table:

(Fictional example.) Read across the rows: the client is fine on Perplexity, where its own site is often cited, and weak on ChatGPT, where a competitor dominates. That's a specific, actionable conversation — and one the average (30%) would have hidden.

Which engines should an agency track?

Start with the engines your clients' customers actually use. In most markets that usually means ChatGPT first, as the most widely used assistant, then Google's AI surfaces, then Perplexity, with Claude and Copilot relevant in some audiences. Add engines when a client asks or the data shows a gap — every engine multiplies the answers you need to collect.

Ranxii tracks ChatGPT, Gemini and Perplexity through their official APIs with web search or grounding switched on, and shows every metric per engine. It does not track Google AI Overviews, AI Mode, Claude or Copilot; if a client needs those, pair it with a tool that does — see the best AI visibility tools for agencies.

Sources

• OpenAI Help Center: Publishers and developers FAQ — OAI-SearchBot, GPTBot and utm_source=chatgpt.com
• Google AI for Developers: Grounding with Google Search
• Perplexity docs: OpenAI compatibility — citations and search results in Sonar responses