So I spent the weekend building cc-filter - a security layer that sits between your prompts and Claude. It intercepts everything before Claude sees it and filters out API keys, database URLs, secrets, basically anything you don't want an AI to access. It uses regex patterns and understands different file types. This works with Claude Code's hook system but also as a standalone tool. I wrote it in Go, so it's fast and ships as single binaries. No dependencies, just download and run. It's configurable because everyone's security needs are different, but it comes with sensible defaults for common secrets.
Been using it for some time now and finally feel comfortable letting Claude help with my actual projects instead of sanitized examples. Hope you find this useful and let me know if you have any feedback