How do I know if an AI tool is safe to use with my personal data?

You check its privacy policy and data usage terms, but honestly, most people don't. And that's a problem. The core question to ask is: will my data be used to train the AI? If the answer is yes, anything you type could, in theory, resurface in someone else's output. This isn't a hypothetical risk. When Samsung employees used ChatGPT to help debug code and summarize meeting notes, they inadvertently leaked sensitive internal data because their conversations were used for model training. After that, Samsung banned the tool. The fix is simple. Many tools offer an opt-out setting. In ChatGPT, for instance, you can find a "Data controls" section in your settings and turn off "Improve the model for everyone." Claude by Anthropic does not train on user inputs by default for its consumer plans. For paid business plans from major providers, data is typically not used for training at all. You should verify this, but it's a common standard. A good rule of thumb: if you wouldn't put the information in a public email, don't put it into a free AI tool without checking the settings first. For highly sensitive work, look for tools that offer a zero-data-retention policy, often found in enterprise plans. If you're just asking for a cookie recipe, it's not a big deal. If you're pasting in a client contract or your company's unreleased product strategy, it's a very big deal. The tool isn't inherently dangerous, but your assumptions about privacy can be.