I've been using Claude Code for almost a year now, but there's always been a lingering question in the back of my head: "Is it really secure? How does it handle and store my data? If it reads my API keys, would it expose them?"
Well, I finally got an answer to at least one of those questions, and honestly, experience is still the best teacher. This week, while working on a personal project using my personal subscription, I was going through some errors and asking Claude Code to help me debug. That's when it happened.
To verify that the right keys were being used, I temporarily printed my API keys in the logs. I forgot to remove them. When I asked Claude Code to run my application to see the error logs, it automatically flagged that it had read the API keys and told me to consider them already exposed.
Since it already happened, I started asking questions: what happens next? How does it handle this? Here's what I found out.
By default, Claude Code does not read your API keys from environment variables, so access is actually restricted. In my case, it was my own mistake that allowed it to read them. But if Claude Code ever does read your API keys, here are three things to keep in mind:
1. Consider them already exposed and rotate your keys immediately.
Don't wait. This is the safest move regardless of anything else.
2. Your conversation logs stay on your computer, not the cloud.
By default, Claude Code stores session transcripts locally on your machine under ~/.claude/projects/ for 30 days. So if your API keys showed up in the logs, they are sitting in plaintext on your local machine. Don't let anyone else access your computer or that folder.
3. The training situation depends on your plan.
This is where I want to be accurate because I see a lot of people get this wrong. If you are on Free, Pro, or Max (consumer plans), your data can be used to train Claude models by default unless you go to your settings and turn it off. If you are on a Team, Enterprise, or API plan, your data is not used for training by default. So whether this is "nothing to worry about" really depends on which plan you are on and whether you have checked your privacy settings.
You can manage this at claude.ai/settings/data-privacy-controls.
So to wrap it up: your API keys are not further exposed beyond your own machine, as long as you clear your local conversation history and make sure no one else has access to your computer. But my verdict stays the same. Treat them as exposed and rotate your keys. Claude Code handles data responsibly, but your security habits are still the last line of defense.