ChatGPT indexes from Bing and commands 78% market share with 87.4% of AI referral traffic. Perplexity pulls heavily from Reddit (46.7% of citations) and has the best crawl-to-referral ratio at under 200:1. Gemini uses Google's index with schema verification and holds 8.65% share. Claude relies on training data with 2.91% share but doubled in one month.

The complete platform comparison

Dimension	ChatGPT	Perplexity	Gemini	Claude	AI Overviews
Search index	Bing	Multi-source	Google	Training data	Google (top 10)
Market share	78%	7%	8.65%	2.91%	48% of queries
Referral traffic share	87.4%	~5%	~4%	<1%	N/A (within Google)
Crawl-to-referral ratio	~1,000:1	<200:1 (best)	~3,500:1	23,951:1 (worst)	N/A
Brand mention correlation	0.664	Low	Moderate	Unknown	Ranking-dependent
Real-time data	Yes (via Bing)	Yes (best)	Yes (via Google)	No	Yes (via Google)
Schema usage	71% of cited pages	Minimal	Actively verifies claims	Indirect	Inherited from Google
Content tone preference	Data-rich, structured	Factual, ignores promotional	Entity-consistent	Deep, comprehensive	Authoritative, top-ranking
Citation stability	Volatile	Moderate	Moderate	Stable	Follows ranking shifts

ChatGPT — the dominant platform

ChatGPT holds 78% of the AI search market and generates 87.4% of all AI referral traffic. It indexes exclusively from Bing, not Google. Brand web mentions (0.664 correlation) and YouTube presence (0.737 correlation) are stronger citation factors than backlinks (0.218).

Key ChatGPT citation behaviours

44.2% of citations come from the first 30% of a page — front-load key content
76.4% of cited pages updated within 30 days — freshness matters
71% of cited pages use schema markup
99.3% of ecommerce responses mention brands, averaging 5.84 brands per response
YouTube mentions have the strongest single correlation (0.737) with AI visibility

ChatGPT optimisation priorities

Get indexed in Bing (submit sitemap to Bing Webmaster Tools)
Build brand mentions across the web
Create YouTube content about your expertise
Allow GPTBot and OAI-SearchBot in robots.txt
Implement IndexNow for rapid Bing indexation

Read the full ChatGPT citation guide

Perplexity — the best ROI per crawl

Perplexity has the best crawl-to-referral ratio of any AI platform at under 200:1, meaning it is far more likely to send traffic to sources it crawls. It pulls 46.7% of its citations from Reddit, operates in real-time, and actively ignores promotional content. At 7% market share, it has the best return on investment per crawl.

Key Perplexity citation behaviours

46.7% of citations come from Reddit — community content dominates
Real-time processing — can cite content published minutes ago
Ignores promotional content — sales-heavy pages get filtered out
Best crawl-to-referral ratio — under 200:1 (compare to Claude's 23,951:1)
Publishers Programme — revenue sharing for cited content
Abandoned advertising entirely — revenue comes from subscriptions and publisher partnerships

Perplexity optimisation priorities

Be active on Reddit with genuine expertise (not promotion)
Join the Perplexity Publishers Programme
Write factual, non-promotional content
Keep content fresh — Perplexity indexes in near real-time
Allow PerplexityBot in robots.txt

Read the full Perplexity citation guide

Gemini — Google's AI layer

Gemini draws directly from Google's search index and uses schema markup to actively verify factual claims. Entity relationships via Google's Knowledge Graph are weighted heavily. At 8.65% market share, Gemini has overtaken Perplexity and will grow as Google integrates it deeper into Search, Workspace, and Android.

Key Gemini citation behaviours

Google index dependent — if Google hasn't indexed your page, Gemini can't cite it
Schema verification — actively cross-references structured data with entity databases
Entity relationships — Knowledge Graph connections carry significant weight
Freshness inherited — uses Google's freshness algorithms
Traditional SEO is prerequisite — strong Google rankings feed Gemini visibility

Gemini optimisation priorities

Ensure full Google indexation via Search Console
Implement comprehensive schema markup
Build entity consistency across Google's ecosystem (GBP, Wikidata, YouTube)
Maintain strong traditional SEO
Allow Google-Extended in robots.txt

Read the full Gemini citation guide

Claude — training data depth

Claude does not browse the web in real time. It relies entirely on training data, making it the only major AI platform where content must be absorbed during training cycles to be cited. Bullet-pointed pages are 30% more likely to be cited. Claude's 2.91% market share doubled in one month, making it the fastest-growing platform by percentage.

Key Claude citation behaviours

No real-time retrieval — relies on training data only
Bullet points — 30% more likely to be cited
Depth over breadth — comprehensive single pages outperform many shallow pages
Stable citations — less volatile than ChatGPT
Worst crawl-to-referral ratio — 23,951:1 (crawls heavily, refers almost no traffic)

Read the full Claude citation guide

AI Overviews — the Google integration

AI Overviews appear in 48% of Google queries, making them the most frequently encountered AI-generated content. They exclusively cite pages that already rank in Google's top 10 results. Multi-modal content (images, video) increases citation likelihood by 156%.

Key AI Overviews behaviours

48% of queries now trigger AI Overviews
Must rank top 10 — only cites existing top results
Multi-modal boost — pages with images/video see 156% higher citation rates
Query fan-out — breaks complex queries into sub-queries, each answered separately
E-E-A-T signals — authority signals heavily weighted

Read the full AI Overviews citation guide

Strategy table: What to prioritise for each platform

Tactic	ChatGPT	Perplexity	Gemini	Claude	AI Overviews
Bing indexation	Essential	Helpful	Not needed	Not needed	Not needed
Google indexation	Indirect	Helpful	Essential	Not needed	Essential
Schema markup	High impact	Low impact	Very high impact	Medium	High impact
Brand mentions	Critical (0.664)	Moderate	Moderate	Helpful	Moderate
YouTube presence	Critical (0.737)	Moderate	High	Helpful	Moderate
Reddit activity	Low	Critical (46.7%)	Low	Low	Low
Content freshness	High	Very high	High	Low (training cycles)	High
Bullet/list formatting	Helpful	Helpful	Helpful	High (+30%)	Helpful
Entity consistency	High	Moderate	Very high	Moderate	High
Traditional SEO	Moderate	Moderate	Essential	Indirect	Essential
Non-promotional tone	Helpful	Essential	Helpful	Helpful	Helpful

The minimum viable strategy

If you can only do five things, do these — they work across all platforms:

Get indexed in both Google and Bing — covers ChatGPT, Gemini, AI Overviews, and Copilot
Implement Organisation, Person, and FAQPage schema — see our schema guide
Build entity consistency — same brand description everywhere
Create structured, data-rich content — answer capsules, tables, bullet lists
Allow all AI crawlers in robots.txt — GPTBot, ClaudeBot, Google-Extended, PerplexityBot

ChatGPT vs Perplexity vs Gemini — How Each Cites Differently