There’s a comforting idea going round that “optimising for AI search” is one job. Get reviews, add some schema, done. It isn’t. The four big AI assistants your customers are using, ChatGPT, Perplexity, Google’s Gemini, and Claude, don’t read the same sources, don’t weight them the same way, and in some cases barely overlap at all. A brand that’s visible in one can be invisible in another.
We pulled together the current citation research on all four, because if you only know that “ChatGPT uses Trustpilot” you’re optimising for a quarter of the picture. Here’s who’s using what.
The quick version
| AI assistant | What it leans on most | What that means for your brand |
|---|---|---|
| ChatGPT | Established, credentialed sources. Trustpilot is its 5th most-cited domain; also heavy on Wikipedia, Reddit and LinkedIn. | Reputation platforms and a solid encyclopedic/entity footprint matter most. |
| Perplexity | Community opinion. Cites Reddit in roughly 47% of commercial-query responses, plus heavy YouTube use. | Authentic discussion and genuine recommendations beat polished marketing. |
| Gemini / Google AI Overviews | Google’s own properties (YouTube, Maps, Shopping) plus Reddit. Gemini and AI Overviews only share ~39% of their sources. | Google Business Profile, Maps reviews and YouTube presence carry real weight, and the two Google surfaces need optimising separately. |
| Claude | Evidence-backed, well-structured content; retrieval aligned with the Brave Search index. | Clear, cited, methodical content and consistent brand mentions win over backlink-stuffing. |
Now the detail, because the “what to do” differs for each.
ChatGPT: the reputation-platform engine
ChatGPT reaches for sources it considers authoritative and well-established. That’s why review platforms do so well here: Trustpilot is currently the fifth most-cited domain on ChatGPT globally, behind only Wikipedia, YouTube, Reddit and LinkedIn (per citation-tracker Promptwatch). It also leans heavily on encyclopedic and professional sources, Wikipedia accounts for a large share of its citations, and Reddit and LinkedIn both feature prominently.
What to do: build a strong, active profile on a recognised reputation platform (Trustpilot especially), and make sure your brand has a clear, consistent entity footprint online, the kind of well-established presence ChatGPT treats as trustworthy. If AI keeps citing Wikipedia and Trustpilot, those are the rooms you want to be in.
Perplexity: the Reddit engine
Perplexity is the outlier, and the most human. One analysis of 10,000 commercial queries found it cites Reddit in 46.7% of its responses, by far the most Reddit-reliant of any assistant, with YouTube close behind at around 32%. It favours these sources precisely because they contain authentic, conversational, community-validated opinion, the opposite of a press release.
What to do: you can’t fake this, and you shouldn’t try (astroturfing Reddit is a fast way to get a brand torched). The legitimate play is to earn genuine presence in the subreddits where your category is discussed, be helpful, answer questions, let real customers talk about you, and to build a real YouTube presence. Perplexity rewards being genuinely talked about, not being advertised.
Gemini and Google AI Overviews: the Google-properties engine (times two)
Google’s AI leans, unsurprisingly, on Google’s own ecosystem. Reddit is the single most-cited source again, but Gemini pulls aggressively on YouTube, Maps and Google Shopping, and recommendation queries surface structured review ecosystems like G2 and Yelp. The catch most people miss: Gemini and the AI Overviews you see in normal search only share about 39% of their top cited domains. They are two different surfaces with two different source pools, and optimising for one leaves a blind spot over the other.
What to do: your Google Business Profile and Google/Maps reviews are doing double duty here, keep them complete and active. Invest in YouTube if your category suits it. And treat Gemini and AI Overviews as separate targets rather than assuming a win in one carries to the other.
Claude: the evidence-and-structure engine
Claude (the assistant this feature’s author uses too) retrieves current information through an index closely aligned with Brave Search, so brands that perform well in that ecosystem surface more readily. More importantly, Claude favours evidence-backed content with clear citations, structured formatting and visible methodology, it’s drawn to content that shows its working. Notably, third-party sources make up the large majority of its citations, and being genuinely mentioned across the web correlates with getting cited far more strongly than traditional backlinks do.
What to do: this is where content quality pays off directly. Well-structured, clearly-sourced, genuinely useful pages, the kind that cite their own evidence, are what Claude reaches for. Thin, unsourced marketing copy doesn’t make the cut.
The pattern underneath all four
Step back and there’s a common thread, even though the specifics differ:
- Reddit and community opinion matter everywhere. It’s the #1 source across ChatGPT, Perplexity, Gemini and AI Overviews. You can’t buy your way in, but you can earn genuine presence.
- Third-party sources dominate. Across the board, roughly 80–85% of AI citations come from sources that aren’t your own website. You influence them, you don’t control them, which is exactly why reviews, mentions and reputation matter so much.
- Entity clarity is the multiplier. Every engine performs better when it can confidently identify who your brand is. A clear, consistent entity footprint (your Organization data, consistent naming, a real presence on the sources these models trust) makes every other signal count for more.
The practical takeaway
Don’t optimise for “AI search” as if it’s one thing. Optimise for the mix your customers actually use:
- For ChatGPT — reputation platforms (Trustpilot) and a strong entity footprint.
- For Perplexity — genuine Reddit and YouTube presence, earned not bought.
- For Gemini / AI Overviews — Google Business Profile, Maps reviews, YouTube, and treat the two Google surfaces separately.
- For Claude — well-structured, clearly-sourced, genuinely useful content.
The good news is these overlap more than they conflict. A brand that’s genuinely well-reviewed, honestly talked about, clearly identified and clearly explained wins across all four. The work is real, but it’s the same work you’d do to deserve the recommendation in the first place.
FAQ
Do all AI assistants use the same sources for recommendations?
No. ChatGPT leans on reputation platforms like Trustpilot and encyclopedic sources; Perplexity cites Reddit in nearly half its commercial-query responses; Google’s Gemini favours Google properties (YouTube, Maps, Shopping) plus Reddit; and Claude favours evidence-backed, well-structured content retrieved via an index aligned with Brave Search. Being visible in one doesn’t guarantee visibility in the others.
Does Perplexity really rely on Reddit that heavily?
Yes. Analysis of 10,000 commercial queries found Perplexity cites Reddit in around 46.7% of responses, making it by far the most Reddit-reliant of the major assistants. It treats authentic community discussion as a high-trust signal.
If I optimise for Google AI Overviews, am I also covered for Gemini?
Not fully. Gemini and AI Overviews share only about 39% of their top cited domains, so they’re effectively two separate surfaces. A brand strong in one can be weak in the other, and both are worth optimising for independently.
What’s the single most useful thing to do across all four?
Get your brand entity clear and consistent, then earn genuine third-party presence (reviews, community discussion, mentions). Around 80-85% of AI citations come from sources other than your own site, and every engine works better when it can confidently identify who you are.
