Quick answer: Firefox cached web content is usually safe to clear, but bookmarks, saved logins, and profiles are separate and should be preserved.
Why this uses C drive space
Firefox can store cache, offline website data, and profile data under AppData. Clearing cache can recover space without resetting the whole browser.
Safe cleanup steps
- Open Firefox settings.
- Go to Privacy & Security.
- Find Cookies and Site Data or Cached Web Content.
- Clear cached content only if you want to preserve logins.
- Restart Firefox after cleanup.
What to avoid
Do not delete the Firefox Profiles folder unless you have a backup and understand profile recovery.
How DiskTidy helps
DiskTidy can help you review temporary files, browser cache, cleanup candidates, and large files before deleting anything. It is designed for local, review-first cleanup instead of blind one-click deletion.