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 uses Brave Search 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	Brave Search + 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)	Yes (via Brave Search)	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 from Bing, not Google. Brand web mentions (0.664 correlation) and YouTube presence (0.737 correlation) are stronger citation factors than backlinks (0.218). Only 11% domain overlap exists between ChatGPT and Perplexity citations. Optimising for one does NOT cover you for the other.

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. It is far more likely to send traffic to sources it crawls. It pulls 46.7% of citations from Reddit, operates in real-time, and ignores promotional content. At 7% market share, it delivers 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. It uses schema markup to verify factual claims. Entity relationships via Google's Knowledge Graph carry heavy weight. At 8.65% market share, Gemini has overtaken Perplexity. It 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 now uses Brave Search for real-time web browsing, plus its training data. Brave indexing matters for Claude's search, not Google or Bing. Bullet-pointed pages are 30% more likely to be cited. Claude's 2.91% market share doubled in one month. It is the fastest-growing platform by percentage.

Key Claude citation behaviours

Brave Search for browsing - uses Brave's index for real-time web lookups, needs Brave browser indexing
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. They are the most frequently encountered AI-generated content. They cite pages that already rank in Google's top 10 results. Multi-modal content (text + images + video + schema) has the strongest correlation with selection at r=0.92. That means up to 317% higher citation rates. Only 13.7% citation overlap with AI Mode. They cite different sources.

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 text + images + video + schema see up to 317% higher citation rates (r=0.92 correlation)
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	Moderate (Brave Search + training)	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 AI search crawlers in robots.txt - OAI-SearchBot, Claude-SearchBot, PerplexityBot, Google-Extended (block training-only crawlers like GPTBot if preferred)

Platform overlap: why you need a multi-platform strategy

Only 11% domain overlap between ChatGPT and Perplexity citations means optimising for one does NOT cover the other. Each platform draws from different sources and weights different signals. Only 13.7% citation overlap between AI Overviews and AI Mode means Google's own AI features cite different sources. Claude needs Brave browser indexing, not just Google or Bing. A single-platform strategy leaves you invisible across 87-89% of other platforms' citation pools.

ChatGPT vs Perplexity vs Gemini