Will the space come back after I clean my C drive?

If you only delete, yes. Measured on one workstation 13 days after a cleanup, deleted-only locations regrew 11.25 GB on the system drive - 10.94 GB in %LOCALAPPDATA%\Temp and 0.31 GB of NVIDIA DXCache - which is roughly 0.87 GB per day, so a delete-only cleanup is undone in about two weeks. Over the same 13 days the relocated applications produced 5.32 GB of new data and every byte of it landed on the destination drive, including 5.76 GB of new Feishu cache. Relocation is what makes the recovered space permanent.

How is this different from 360 Total Security, Tencent PC Manager, or CCleaner?

The Chinese PC suites do relocate software off C: using symbolic links, and that part works. Two things differ. First, what moves: they move installed software chosen from a vendor-maintained list, while this relocates any directory you name - including developer toolchain caches such as NuGet, npm, pip, Playwright, Cargo, Gradle and the Unreal Engine derived data cache, which are usually where the regrowth actually is. Second, what comes attached: this is an MIT-licensed script that runs and exits, with no background service, no advertising, no upsells, and uninstalling means deleting a folder. CCleaner and Windows Storage Sense only delete; Storage Sense additionally manages the system drive only, does not touch browser caches, skips app temp files from Teams, Spotify and Discord, and by default runs only once the disk is already nearly full.

How long does it take to clean and relocate?

The documented run took about 25 minutes end to end on a 299 GB system drive: a few minutes of scanning, then the deletions, then roughly 11 minutes to copy 29 GB across five relocations from SSD to SSD. It recovered 43.7 GB, taking free space from 19.0 GB to 62.7 GB. That is a one-time cost, and 13 days later the drive still had 61.4 GB free - compared with re-running a delete-only cleaner every two weeks indefinitely.

Can it move an application that is not on its supported list?

Yes. The relocation script takes any source and destination path, so there is no vendor list to wait on. The bundled application atlas documents which subdirectories are safe to delete for applications that have been verified firsthand, but the relocation machinery itself is generic and works on any directory on an NTFS volume.

DriveKeeper — Windows Disk Cleanup That Stays Clean

Q: Will cleaning app caches delete my chat history?

No, if you delete at the right granularity. In Chromium-based desktop apps the disposable items are Cache\Cache_Data, Code Cache, GPUCache, the shader caches, and Service Worker\CacheStorage. Login state lives in Local Storage, Cookies, and persistent storage databases, and application data lives in IndexedDB and Service Worker\Database - deleting those logs you out or loses local drafts. Deleting the whole profile folder to clear a cache is the common mistake. For WeChat and WeCom this skill does not touch the data at all and points you at the app's own storage setting instead.

Q: Is it safe to delete the Unreal Engine DerivedDataCache?

Yes. Epic's documentation states that content stored in the DDC is disposable and Unreal Engine regenerates it from .uasset files at any time. Relocating it is still preferable to deleting it, because deleting means recompiling shaders. Unreal Engine 5.4 and newer use Zen Store as the local DDC by default, so relocate %LOCALAPPDATA%\UnrealEngine\Common to cover both in one move, after stopping zenserver.exe.

Q: Does robocopy exit code 1 mean the copy failed?

No. robocopy exit codes are a bit field, not a boolean. 0 means nothing needed copying, 1 means files were copied successfully, and 8 is the first code that indicates a real failure. Testing $? or $LASTEXITCODE -ne 0 in PowerShell will report a perfectly good copy as a failure. Test for $LASTEXITCODE -lt 8 instead.

Q: Why does my PowerShell script fail with null-reference errors on valid lines?

Windows PowerShell 5.1 reads a UTF-8 file without a byte order mark as ANSI, using the system code page. Non-ASCII characters in comments corrupt the byte stream and can swallow adjacent statements, so variables silently become null and the script half-runs without ever raising an error. Keep helper .ps1 files pure ASCII, or save them as UTF-8 with BOM.

Q: Why clean early instead of waiting until the disk is actually full?

A Windows volume that reaches zero free bytes does not fail loudly; writes in progress fail partway, and SQLite databases are especially vulnerable. In the incident behind this project, a full C: drive truncated Chrome's History database into an empty shell, and Chrome kept running without recording anything until it was restarted, so the loss was only noticed days later. Treat a nearly full disk as an active data-loss risk rather than a housekeeping chore.

Why deleting doesn't hold

One real workstation, measured 13 days after a cleanup. Same machine, same period — the only difference is whether the location was deleted or relocated.

What was done	At cleanup	13 days later	Where the growth landed
Deleted only — `%LOCALAPPDATA%\Temp`	0 GB	10.94 GB	back on C:
Deleted only — NVIDIA `DXCache`	0 GB	0.31 GB	back on C:
Relocated — Feishu/Lark data	3.69 GB	9.45 GB	D: — 5.76 GB of new cache
Relocated — agent session transcripts	16.18 GB	16.19 GB	D:
Relocated — NuGet + Playwright	6.71 GB	6.71 GB	D:

11.25 GB crawled back onto C: in 13 days — about 0.87 GB/day. A delete-only cleanup is undone in roughly two weeks. Over the same period the relocated set grew 5.32 GB net and not one byte of it went to C:.

That is the whole mechanism: a junction is a filesystem-level redirect, resolved below the application layer. The app opens the same path it always did and never learns that its data now lives on another volume — so its future growth follows the link automatically.

How it compares

To be fair to them: the big Chinese PC suites do use symbolic links to move installed software off C:, and that part works. The differences that matter are what gets moved and what comes attached.

	360 / Tencent PC suites	CCleaner / Storage Sense	DriveKeeper
One-click junk cleanup	Yes	Yes	Yes — allowlist, dry-run by default
Relocates with junctions	Yes	No	Yes
Who decides what moves	The vendor's software list	—	You do — any directory or toolchain
Dev toolchain caches via env vars	No	No	NuGet, npm, pip, Playwright, Cargo, Gradle, UE DDC
Per-subdirectory safe/unsafe rules	No	No	30+ apps, extensible
Byte-level verify before deleting source	Not documented	N/A	Yes — mismatch aborts
Background service, ads, upsells	Yes	Some	None — runs and exits
Uninstall	Uninstaller flow	Uninstaller flow	Delete a folder
Open source	No	No	MIT

You point it at anything

There is no vendor list to wait on:

.\Move-AppData.ps1 -Source "$env:APPDATA\SomeAppNobodySupports" -Destination "D:\AppData\SomeApp"

For reference, Windows Storage Sense manages the system drive only, does not touch browser caches, skips app temp files from Teams/Spotify/Discord, and by default runs only once the disk is already nearly full.

What it costs you: about 25 minutes, once

A few minutes of scanning, the deletions, then roughly 11 minutes to copy 29 GB across five relocations, SSD to SSD.

That run recovered 43.7 GB on a 299 GB system drive — 19.0 GB free to 62.7 GB, with zero data lost. Thirteen days later the drive was still at 61.4 GB free. The alternative is re-running a delete-only cleaner every two weeks, indefinitely.

Reclaiming space is easy if you don't mind losing things

This is built the other way round.

Deletion is allowlist-only. It cannot be pointed at an arbitrary folder — structural, not a policy you have to trust.
Dry-run by default. Nothing is removed until you pass -Execute.
Anything a human created or accumulated gets moved, never deleted.
Byte-level verification before any source is deleted. Bytes and file counts are recounted independently on both sides; a mismatch aborts and restores the original.

The hard part isn't deleting — it's knowing which subdirectory is disposable. In a Chromium-based app, Service Worker\CacheStorage is disposable and often over 1.5 GB per profile, but its sibling Service Worker\Database is not, and Local Storage holds your login token. Folder-level thinking logs you out.

Probe for locksRename the directory in place. Success means nothing holds a handle; failure means stop rather than force.
Copyrobocopy /E /COPY:DAT /DCOPY:DAT. Exit codes below 8 are success.
Recount independentlyTotal bytes and file count on both sides must match exactly. Do not trust the copy tool's summary.
Delete the sourceOnly now. Until this step the original is fully intact, which is what makes the operation abandonable at any earlier moment.
Create the junctionmklink /J. From here, future writes follow the link automatically.
Confirm live writesStart the app and verify new files appear on the destination. A silently failed junction looks identical to a working one until you check.

Install

git clone https://github.com/linad3d/drivekeeper.git
Copy-Item -Recurse drivekeeper\skills\windows-disk-cleanup "$env:USERPROFILE\.claude\skills\"

Then describe the problem in plain language:

my C drive is down to 8GB, figure out what's eating it and clean up what's safe

Or run the scripts without Claude

.\Scan-DiskUsage.ps1 -Path C:\ -MinGB 0.3          # see what is actually big
.\Invoke-SafeClean.ps1                             # preview - deletes nothing
.\Invoke-SafeClean.ps1 -Category GPU,DevTools -Execute
.\Move-AppData.ps1 -Source "$env:APPDATA\SomeApp" -Destination "D:\AppData\SomeApp"
.\Test-Migration.ps1 -Watch "D:\AppData\SomeApp"    # prove the redirect is live

Windows 10/11 · PowerShell 5.1+ · NTFS on both sides · elevation for mklink, C:\ProgramData and C:\Windows\Temp.

Frequently asked questions

Will the space come back?

If you only delete, yes. Measured 13 days after a cleanup, deleted-only locations regrew 11.25 GB on the system drive (10.94 GB of %LOCALAPPDATA%\Temp plus 0.31 GB of NVIDIA DXCache) — about 0.87 GB/day, so a delete-only cleanup is undone in roughly two weeks. Over the same period the relocated applications produced 5.32 GB of new data and every byte landed on the destination drive, including 5.76 GB of new Feishu cache.

How is this different from 360, Tencent PC Manager, or CCleaner?

The Chinese PC suites do relocate software off C: with symbolic links, and that works. Two things differ. What moves: they move installed software from a vendor-maintained list; this relocates any directory you name, including developer toolchain caches (NuGet, npm, pip, Playwright, Cargo, Gradle, Unreal Engine DDC) where the regrowth usually is. What comes attached: this is an MIT-licensed script that runs and exits — no background service, no ads, no upsells, and uninstalling means deleting a folder. CCleaner and Storage Sense only delete.

How long does it take?

About 25 minutes end to end in the documented run: a few minutes scanning, the deletions, then ~11 minutes copying 29 GB across five relocations. One-time. It recovered 43.7 GB (19.0 → 62.7 GB free on a 299 GB drive), and 13 days later the drive still had 61.4 GB free.

Can it move an app that isn't on the supported list?

Yes. Move-AppData.ps1 takes any source and destination — there is no vendor list to wait on. The bundled atlas documents which subdirectories are safe for apps verified firsthand; the relocation machinery itself is generic and works on any directory on an NTFS volume.

Will cleaning app caches delete my chat history?

No, if you delete at the right granularity. The disposable items are Cache\Cache_Data, Code Cache, GPUCache, the shader caches, and Service Worker\CacheStorage. Login state lives in Local Storage and Cookies; app data lives in IndexedDB and Service Worker\Database. For WeChat and WeCom the skill does not touch the data at all — it points you at the app's own storage setting.

Are NTFS junctions safe? Will apps break?

A junction is a filesystem-level redirect resolved below the application layer, so apps open it as an ordinary directory — which is also why future writes follow it automatically. It requires NTFS on both sides and the same machine: never point one at a network share, a non-NTFS volume, or a removable drive that may be absent at boot.

Is it safe to delete the Unreal Engine DerivedDataCache?

Yes. Epic's documentation states DDC contents are disposable and regenerated from .uasset files. Relocating is still preferable, since deleting means recompiling shaders. UE 5.4+ uses Zen Store as the local DDC by default, so relocating %LOCALAPPDATA%\UnrealEngine\Common covers both — stop zenserver.exe first.

Does robocopy exit code 1 mean the copy failed?

No. robocopy exit codes are a bit field: 0 means nothing needed copying, 1 means files were copied successfully, and 8 is the first code indicating a real failure. Test $LASTEXITCODE -lt 8, not $?.

Why does my PowerShell script fail with null-reference errors on valid lines?

Windows PowerShell 5.1 reads a UTF-8 file without a BOM as ANSI. Non-ASCII characters in comments corrupt the byte stream and can swallow adjacent statements, so variables silently become $null and the script half-runs without erroring. Keep helper .ps1 files pure ASCII, or save as UTF-8 with BOM.

Why clean early instead of waiting until the disk is full?

Writes in progress fail partway, and SQLite databases are especially vulnerable. In the incident behind this project, a full C: drive truncated Chrome's History database into an empty shell and Chrome kept running without recording anything until restarted — the loss was found days later. Treat a nearly full disk as an active data-loss risk.

中文说明

清理工具删完就长回来。这个把该映射的映射掉，所以不会。

一个 Claude Code 技能 + 独立可用的 PowerShell 工具包：先把爆满的 C 盘救回来，再用 NTFS 目录连接（junction）和环境变量，把那些反复回涨的目录搬到别的盘。应用还往原来的路径写，字节落在别处。

实测（同一台机器，清理后第 13 天）：只删没搬的地方回涨了 11.25 GB 到 C 盘（%LOCALAPPDATA%\Temp 10.94 GB + NVIDIA DXCache 0.31 GB），约 0.87 GB/天—— 也就是说，一次只删的清理大约两周就白干了。同期做了映射的那批新增 5.32 GB， 没有一个字节进 C 盘，其中光飞书就新增了 5.76 GB 缓存，全落在 D 盘。

和 360 安全卫士 / QQ电脑管家比：平心而论，它们的「C盘搬家」确实也是用符号链接实现的，这部分没问题。区别在两点——搬什么由谁决定：它们搬的是厂商内置列表里的已安装软件，而这个是你指哪搬哪，包括 NuGet、npm、pip、Playwright、Cargo、Gradle、虚幻引擎 DDC 这些真正在反复涨的开发者缓存；以及附带了什么：这是个 MIT 开源脚本，跑完就退出，没有常驻后台、没有广告推广，卸载就是删个文件夹。

要花多久：那次完整跑下来约 25 分钟（扫描几分钟 + 删除 + 约 11 分钟复制 29 GB 完成 5 项迁移），释放 43.7 GB，零数据丢失。一次性投入。

完整中文文档 →