BitBroom

A safety-first, open-source disk cleaner for Windows.

Reclaim gigabytes of hidden junk — without the fear, the ads, the upsells, or the registry-cleaner snake oil.

bitbroom.app/cleaner

---

Why BitBroom exists

Every Windows user eventually hits the same wall: the C: drive fills up and nobody knows why. The usual suspects hide in places Explorer won't show you — shader caches, crash dumps, update leftovers, WSL virtual disks that never shrink, Electron apps hoarding gigabytes, a search index gone feral, or (in 2026) a literal Windows bug growing a log file to 500 GB.

The tools that promise to fix this have become part of the problem: ads, telemetry, subscription nags, fake "registry optimization", and cleaning logic reckless enough to earn CVEs. BitBroom is the opposite bet: a cleaner you can read the source of, that treats your data like it's radioactive, and that tells you the truth.

What it does

Clean	60 research-backed categories: Windows temp & update caches, crash dumps & kernel reports, Windows Error Reporting, Defender logs, thumbnail caches, browser caches (Chrome/Edge/Brave/Firefox/Opera/Vivaldi), Discord/Slack/Teams/Zoom/Spotify/Adobe/OBS caches, Apple device updates (IPSW), NVIDIA/AMD/Intel shader caches, Steam/Epic/EA/Battle.net/Ubisoft caches, Unity/Unreal engine caches, npm/pip/uv/NuGet/cargo/Go/Gradle/Maven dev caches, OneDrive/Docker logs — plus your own custom folders with per-folder age limits.
Duplicates	Content-verified duplicate finder (size → head hash → full SHA-256, so it never lies about a match), an empty-folder finder, and a Dev junk mode that finds regenerable build folders (node_modules, target, .venv, dist, .next, …) — only when they sit next to a real project manifest, and never inside installed apps (Electron/Squirrel/AppData runtime locations are refused). Recycle Bin-only deletion, and one copy of every duplicate group always survives — enforced in the engine, not just the UI.
Disk Analyzer	"Where did my space go?" — parallel folder-size treeview, the 100 largest files, a by-file-type breakdown, CSV export, and open-in-Explorer / recycle actions.
Space Hogs	Report-only detector for the big hidden consumers: hiberfil.sys, page files, WSL/Docker .vhdx disks, System Restore usage, the Windows Search index, the WinSxS component store, DriverStore, Windows Installer cache, oversized Outlook OSTs, the Downloads folder, the CapabilityAccessManager.db-wal Windows bug — each with the safe, supported fix explained.
Tools	One-click supported maintenance: DISM component-store cleanup & analysis, WSL/Docker virtual-disk compaction (reclaims the empty space .vhdx files never give back — non-destructive, works on every Windows edition), OneDrive "free up space" (bulk online-only, nothing deleted), old-driver removal (keeps the newest of every driver family; Windows itself refuses in-use packages), hibernation off/reduced/on, DNS flush, Explorer restart, System Restore usage. Official Windows mechanisms only (diskpart, attrib, pnputil, DISM, powercfg), output streamed live.
CLI	bitbroom-cli — scan/clean/hogs/analyze/dupes/devjunk with --dry-run, --json, exit codes for scripting.
Automation	Scheduled cleaning of the safe default set via Windows Task Scheduler (Settings → Scheduled cleaning — free, no Pro tier). Per-folder exclusions are enforced engine-deep, and an optional Recycle Bin mode gives every clean an undo window.
Native look	Windows 11 Fluent design end-to-end: acrylic wallpaper-blur backdrop (taskbar-style), native NavigationView, Fluent controls and title bar via the MIT-licensed WPF UI library — plus a branded startup animation, page transitions, staggered reveals, shimmer progress and inertial smooth scrolling.

The safety model (the actual point)

Read docs/SAFETY.md for the full design. The short version:

1. A central PathGuard validates every deletion twice — once when a rule resolves, once immediately before each file is deleted. Rules are anchored to known bases (%LocalAppData%, %WinDir%, …) and can never escape them; drive roots, System32, WinSxS, Program Files, your profile, Documents, Desktop, Pictures, Downloads, and OneDrive folders are rejected structurally, not by convention.
2. Junctions and symlinks are never followed — not while scanning, not while resolving wildcards, not while deleting. A junction planted inside a temp folder cannot redirect BitBroom anywhere (the exact bug class behind CCleaner's CVE-2025-3025).
3. Cloud placeholders are never touched. Deleting a OneDrive Files-On-Demand stub deletes the cloud copy — BitBroom refuses files with recall/offline attributes outright.
4. Fresh files are kept. Anything modified or created in the last 24 h (configurable) is skipped in temp categories, so running installers and apps are never disturbed.
5. Files in use are skipped silently — never forced, never scheduled for boot-time deletion.
6. Every deletion is written to a plain-text audit log with full path and size. There is a simulation mode that only writes the log and deletes nothing.
7. No registry cleaner. Ever. The consensus from Windows internals experts (Mark Russinovich): negligible benefit, real risk. Same for prefetch purging — a myth that makes boots slower.
8. No telemetry, ever. No tracking, no accounts, no crash reporting. The GUI's only network touch is an optional once-per-launch GitHub version check (off = zero network requests); updates download only when you click Install and are SHA-256-verified against the release manifest before running. The engine and CLI have no network code. The cleaning engine has zero third-party dependencies; the GUI's only dependency is the MIT-licensed, source-auditable WPF UI library (Fluent controls — no network code).

The safety engine is enforced by a test suite whose flagship test plants a junction inside a cleaned folder pointing at a canary file — the suite fails if the canary is ever touched.

Install

Portable (recommended): grab BitBroom-portable-win-x64.zip from Releases, extract, run BitBroom.exe. Self-contained — no .NET runtime install needed.

Installer: BitBroom-<version>-setup.exe from Releases.

Build from source: see docs/BUILDING.md.

BitBroom runs fine without administrator rights (per-user categories). System categories (Windows Temp, Update cache, logs, dumps) unlock via the in-app Restart as administrator button. No forced UAC prompt at every launch.

CLI quick start

bitbroom-cli list                                    # all categories with risk levels
bitbroom-cli scan                                    # measure the safe default set (read-only)
bitbroom-cli clean --dry-run                         # full preview: logs everything, deletes nothing
bitbroom-cli clean --yes                             # clean the default set
bitbroom-cli clean --categories user-temp,nvidia-caches --yes
bitbroom-cli hogs                                    # hidden space-consumer report
bitbroom-cli analyze D:\ --depth 3 --top 50          # folder size breakdown + file types
bitbroom-cli dupes D:\Photos --min-size 5            # content-verified duplicate report
bitbroom-cli scan --json                             # machine-readable everything

Full reference: docs/CLI.md.

What BitBroom deliberately does NOT do

Documented with sources in docs/CATEGORIES.md:

• ❌ Registry cleaning (risk without benefit)
• ❌ Prefetch / ReadyBoot purging (slows your next boots; Windows self-manages it)
• ❌ C:\Windows\Installer deletion (breaks uninstall/repair of installed software)
• ❌ Browser cookies/history/passwords (that's your data, not junk)
• ❌ Office Document Cache (can hold unsynced edits)
• ❌ "Free RAM" / "boost gaming" / other placebo buttons
• ❌ DISM /ResetBase (permanently removes update rollback — not worth it)
• ❌ Secure-wipe of cleaned files (pointless on SSDs, punishing on any drive)
• ❌ winapp2.ini imports (thousands of unvetted third-party delete rules would bypass the tested guard model — every BitBroom category is individually researched and test-gated)
• ❌ Startup managers / uninstallers / driver updaters (Windows Settings does this natively; suite-creep is how cleaners become the problem)

The BitBroom family

• 🧹 BitBroom (this repo) — cleans the junk you don't need.
• 🟠 BitBroom Rescue — brings back the files you do: safety-first data recovery (NTFS/FAT32/exFAT undelete, Recycle Bin, shadow copies, signature carving, clone-first imaging for failing drives). The source drive is opened read-only, always.

Project layout

src/BitBroom.Core/    engine: PathGuard, walker, SafeDeleter, rules, catalog, analyzer,
                      duplicate/empty-folder finders, hogs, scheduling (zero third-party deps)
src/BitBroom.App/     WPF GUI — Windows 11 Fluent via WPF UI (MIT), acrylic backdrop
src/BitBroom.Cli/     bitbroom-cli
tests/                safety-critical test suite (junction canary & friends)
docs/                 RESEARCH, SAFETY, CATEGORIES, CLI, BUILDING

"Windows protected your PC"?

On first launch Windows may show a blue SmartScreen prompt ("Windows protected your PC"). That's expected for a new app that hasn't yet built download reputation with Microsoft — it is not a malware detection. Click More info → Run anyway. BitBroom is open source (read every line here) and each release ships a SHA256SUMS.txt so you can verify your download is byte-for-byte the published build. The warning fades on its own as more people install a given release.

Requirements

• Windows 10 x64 (1809+) or Windows 11 (x64 / ARM64 builds available)
• No runtime dependencies (self-contained binaries)

Contributing

PRs welcome — especially new cleaning categories with sources and safety-test coverage. Read CONTRIBUTING.md first; category proposals must pass the CatalogSanityTests gate.

License

MIT. Research grounded in Microsoft documentation, vendor guidance, and years of community knowledge (Winapp2.ini, BleachBit) — see docs/RESEARCH.md for the full source list.