Quick Answer
Anthropic does not use free-tier conversations for training by default, and Pro users have even stronger protections.
Detailed Answer
Anthropic has one of the strongest privacy stances among AI providers. Free-tier conversations may be used for safety research but not general model training without consent. Pro subscribers have explicit data protections. Claude does not remember between conversations unless you use the Projects feature. For enterprise use, Anthropic offers data processing agreements that guarantee your data stays private.
Find Your Own Answer
The best way to decide is to try them yourself. Council lets you compare multiple AI responses to the same question.