Googlebot: Blocking Googlebot removes your pages from Google Search. To opt out of Gemini training only, block the Google-Extended token instead.
Mediapartners-Google: If your site shows AdSense ads, do not block it. Without it, AdSense cannot read your pages and ads become less relevant.
AdsBot-Google: AdsBot ignores the "User-agent: *" group. You must name it to block it.
Bingbot: Blocking Bingbot also removes you from search engines that use the Bing index, such as DuckDuckGo and Yahoo.
Applebot: To stay in Siri and Spotlight but opt out of Apple AI training, block the Applebot-Extended token instead.
GPTBot: Blocking GPTBot does not remove you from ChatGPT search. That is OAI-SearchBot, which has its own token.
ChatGPT-User: Because it acts for a user, OpenAI says robots.txt rules may not apply to it.
ClaudeBot: Anthropic also runs Claude-SearchBot (search) and Claude-User (user requests). Each has its own token.
Perplexity-User: Because it acts for a user, Perplexity says it generally ignores robots.txt.
Bytespider: Many site owners report it does not always follow robots.txt. Check its Trap Room record, and consider a server-level block too.
facebookexternalhit: Blocking it breaks link previews on Meta apps. Meta says it may skip robots.txt for security and integrity checks.
Google-InspectionTool: Blocking it stops Search Console from testing your pages. It does not affect Google Search itself.
Storebot-Google: If you sell things, blocking it can keep your products out of Google Shopping.
cohere-ai: Cohere uses two names, cohere-ai and cohere-training-data-crawler. The rule blocks both.
Screaming Frog SEO Spider: It reads robots.txt by default, but its user can switch that off.
UptimeRobot: It only visits pages someone has asked it to watch. To stop it, the person who set up the monitor has to remove it.
Pingdom: It only visits pages someone has asked it to watch.
Wget: Wget reads robots.txt when it downloads a site recursively, but not for single files.
Scrapy: New Scrapy projects read robots.txt by default, but their authors can turn that off.
Google-Extended: Blocking Google-Extended does not affect Google Search.
Applebot-Extended: Blocking Applebot-Extended does not remove you from Siri or Spotlight.