There is no single AI engine to optimize for. The usage numbers say one thing and the referral numbers say another, and your own buyers may say a third. So start with them.
The short version: ask your buyers, check your analytics, then test the top two engines. Here is the data behind that advice.
How many people use these tools?
Pew Research surveyed 5,119 US adults between February 17 and 23, 2026. It found that 44% have used ChatGPT, up from 34% in 2025, 23% in 2024 and 18% in 2023. About half of US adults (49%) now use any AI chatbot, up from 33% in 2024, and about a quarter (24%) use chatbots daily. Pew changed the question wording in 2026 to cover other chatbots, so the jump is not perfectly comparable with earlier years.
Where do AI visitors actually come from?
SE Ranking analysed data from 101,574 websites for January 2025 to April 2026. AI platforms sent 0.32% of all website traffic, up from 0.24% in 2025 and 0.02% in 2024. Of that AI traffic:
| Platform | Share of AI referral traffic |
|---|---|
| ChatGPT | 74.78% |
| Gemini | 11.56% |
| Perplexity | 7.23% |
| Copilot | 3.51% |
| Claude | 2.62% |
ChatGPT's share fell from 79.74% in 2025, even though its referrals grew 27%. Claude's referrals grew 320% and Gemini's 231%. SE Ranking notes the results may not reflect every website, industry or region. Its list of tracked platforms does not include Google's AI Overviews, so treat this as a partial picture.
Why not just pick the biggest?
Because "biggest" depends on who you measure. Usage across all adults is not the same as referrals to business sites, and referrals to one industry can look very different from the average. A figure that is true for everyone may be wrong for your buyers.
A buyer-led way to choose
| Step | What to do | What it tells you |
|---|---|---|
| 1 | Ask ten recent customers which AI tool, if any, they used before they contacted you | Where your real buyers ask |
| 2 | Look at the referral sources in your analytics for visits from AI tools | Which engines already send you traffic |
| 3 | Run the five-question test on the top two | Whether you are named, and what is said |
If you cannot get that data yet, our rule of thumb is to test ChatGPT and one engine that searches the live web, then add the rest once you see referrals. That is a judgment, not a finding.
Want all three tested at once? The free AI Visibility Score asks ChatGPT, Claude, and Perplexity and scores the answers out of 100.
Sources
Data checked October 18, 2026.