A new study by Profound looked at how OpenAI’s ChatGPT, Google AI Overviews, and Perplexity gather their information. It found that ChatGPT mostly pulls information from Wikipedia, while Google AI Overviews and Perplexity rely more on Reddit.

The study analyzed 30 million citations from August 2024 to June 2025.

Here are the key results:

• ChatGPT’s top source: Wikipedia (47.9%)
• Google AI Overviews’ top source: Reddit (21%)
• Perplexity’s top source: Reddit (46.7%) 

For Google AI Overviews, the top sources were:

1. Reddit
2. YouTube
3. Quora
4. Wikipedia (only 5.7%)

These findings show that different AI tools pull from very different parts of the web to build their answers.

It seems that, at least for now, Reddit gets a lot of attention across all three platforms — ChatGPT, Google AI Overviews, and Perplexity — but especially with Google and Perplexity.

There’s also a forum discussion happening over on X.

Update: A few hours later, the team at Ahrefs shared a similar study — but their results are a bit different.