What are user-triggered fetchers?
A user-triggered fetcher is a bot that opens a page only because a person asked an assistant about it, for example ChatGPT-User, Claude-User or Perplexity-User. It is not a crawler that builds an index. Providers state that robots.txt rules may be handled differently for these requests, so check each provider's documentation.
Why distinguish them?
In your logs, a spike of ChatGPT-User means people are asking about your pages right now. A spike of an indexing bot means a crawl. They need different decisions: you may want user-triggered visits to succeed even if you limit training.
Example: someone pastes your pricing URL into ChatGPT and asks for a summary; your logs show one request from ChatGPT-User, not a crawl.
Where to read the details
OpenAI documents its bots at platform.openai.com/docs/bots, Anthropic in its support article on crawlers, and Perplexity in its bot documentation. Names and behaviour change, so re-check them before you write rules.
Check which AI crawlers your site allowsFree AI crawler checker: GPTBot, ClaudeBot, PerplexityBot and more.