AI Search Engines Compared
ChatGPT vs Perplexity vs Google AI Overviews
Six AI platforms can cite your website in their answers. Each finds content differently. Here's what you need to know about each one.
Side-by-Side Comparison
| Platform | How It Finds Sites | Crawler | Can You Opt Out? | Audience |
|---|---|---|---|---|
| Google AI Overviews | Google's own index | Googlebot (standard) | No (tied to Google index) | Billions |
| ChatGPT Search | Bing index + OAI-SearchBot | OAI-SearchBot | Yes (block OAI-SearchBot) | Hundreds of millions |
| Perplexity | Own index via PerplexityBot | PerplexityBot | Yes (block PerplexityBot) | Tens of millions |
| Microsoft Copilot | Bing index (no own crawler) | None (uses Bingbot) | No (tied to Bing index) | Hundreds of millions (Bing, Edge, Windows) |
| Claude | ClaudeBot + web search | ClaudeBot, Claude-Web | Yes (block ClaudeBot) | Millions |
| Gemini | Google index | Google-Extended | Partial (block Google-Extended for training) | Hundreds of millions |
Platform Deep Dives
Google AI Overviews
Billions users
ChatGPT Search
Hundreds of millions users
Perplexity
Tens of millions users
Microsoft Copilot
Hundreds of millions (Bing, Edge, Windows) users
Claude
Millions users
Gemini
Hundreds of millions users
What You Can Control
Your levers for AI search visibility vary by platform.
| Action | ChatGPT | Perplexity | AI Overviews | Copilot |
|---|---|---|---|---|
| Block via robots.txt | Yes | Yes | No | No |
| Bing indexing matters | Yes | No | No | Yes |
| Google indexing matters | No | No | Yes | No |
| Block training separately | Yes (GPTBot) | Same bot | Yes (Google-Extended) | N/A |
Quick Recommendations
Want maximum AI visibility?
Allow all AI crawlers, submit your sitemap to both Google and Bing, use structured data, and keep content fresh. Use our robots.txt generator to set everything to "Allow".
Want citations but no training?
Allow OAI-SearchBot, ChatGPT-User, PerplexityBot, and Claude-Web. Block GPTBot, ClaudeBot, CCBot, and Google-Extended. This gives you search citations without contributing to model training.
Want to block all AI access?
Block every AI crawler in robots.txt. Note: you can't block Google AI Overviews or Copilot this way since they use the standard search index. You'd need to de-index from Google/Bing entirely, which is rarely worth it.
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Frequently Asked Questions
Which AI search engine has the most users?
Google AI Overviews reaches the most people since it's built into Google Search (billions of users). ChatGPT has hundreds of millions of monthly users. Perplexity has tens of millions. Microsoft Copilot is integrated into Bing, Edge, and Windows, reaching hundreds of millions.
Which AI search engine sends the most referral traffic?
It varies by niche. Google AI Overviews has the largest potential audience but may reduce clicks when the overview fully answers the query. Perplexity is known for clean source attribution with numbered citations. ChatGPT Search includes clickable source links. Early data suggests Perplexity and ChatGPT send meaningful referral traffic to cited sites.
Can I optimize for all AI search engines at once?
Mostly yes. The fundamentals are the same: allow AI crawlers in robots.txt, create authoritative content, use structured data, and make sure your site is crawlable. The main difference is that ChatGPT and Copilot depend on Bing, while Perplexity and Claude have their own crawlers.
Which AI crawlers should I definitely allow?
At minimum, allow OAI-SearchBot (ChatGPT Search citations), PerplexityBot (Perplexity search), and ChatGPT-User (ChatGPT browsing). These are the crawlers that directly lead to your site being cited with a source link. Training crawlers like GPTBot are a separate decision.
Does ranking on Google help with ChatGPT?
Not directly. ChatGPT uses Bing, not Google. However, pages that rank well on Google often rank well on Bing too, since many SEO fundamentals overlap. For ChatGPT specifically, focus on Bing Webmaster Tools and make sure OAI-SearchBot is allowed.
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