Firefox
Firefox stores per-profile browsing data in SQLite databases and on-disk cache folders, including HTTP disk cache entries, startup and script caches, favicons, thumbnail previews, and SQLite WAL/SHM sidecar files used while databases are active. Over time these files can become bloated, fragmented, or out of sync after browser updates, crashes, or interrupted writes; Kudu clears disposable cache data and vacuums Firefox’s SQLite databases to reclaim space without touching bookmarks, saved passwords, history, cookies, extensions, or account data.
Why clean Firefox?
- Corrupted HTTP disk cache entries can make pages load with missing images, broken styles, or old content until Firefox refetches them from the network
- Stale startup and script cache files after a Firefox update can cause an unusually slow first launch, delayed tab restore, or brief UI hangs while caches rebuild
- Oversized favicon and thumbnail databases can consume hundreds of megabytes and make site icons or new tab previews appear blank or outdated
- Crash leftovers in SQLite WAL and SHM files can keep profile storage larger than expected and contribute to repeated database recovery work on startup
- SQLite page fragmentation builds up as Firefox rewrites places, favicons, and other profile databases, and VACUUM compacts them by rewriting pages without deleting your actual rows of data
- A bloated profile cache can increase disk activity during browsing, which users notice as tab switching pauses, longer shutdowns, or sluggish startup on older SSDs and HDDs
- Interrupted cache writes can leave inconsistent local cache state that shows up as pages refusing to update properly until the browser cache is cleared and recreated
Cache paths Kudu targets
These databases are vacuumed (compacted) — no data is deleted. SQLite VACUUM reclaims wasted space left over from normal usage.
Windows
%AppData%/Mozilla/Firefox/Profiles |
macOS
~/Library/Application Support/Firefox/Profiles |
Linux
~/.mozilla/firefox |
Common questions about Firefox
Download Kudu and reclaim your disk space.
Available on Windows, macOS, and Linux. No account required, no feature gates, no telemetry without consent. All cleaning targets are open source and community-auditable.