User folder migration
Move 11 types of folders — desktop, documents, downloads, pictures, videos, music and more — to a data drive, and update the system's Known Folder registry so File Explorer still shows "Desktop".
v1.5.1 · Open source · Free · MIT License
Slim down your C: drive,
Slim down your C: drive,
apps keep working
C-Slim moves your desktop, documents, downloads, AppData, large programs and Store apps to a data drive, then links them back to the original paths with Windows' native directory junctions — to the system and your software, nothing changed, only C: got lighter.
11
user folder types you can move
17
script modules, each with its own role
100%
open source, free, no ads, no bundles
MIT
license — use and modify freely
Features
Move what should move, keep what should stay
Six migration and cleanup capabilities — run them individually or all at once. Every action tells you what it is about to do, then asks whether you want it.
Large program migration
Move bulky software out of C:\Program Files to a data drive, leaving a directory junction at the original location. The app, its shortcuts and uninstall entry all keep working.
AppData redirection
WeChat/QQ chat files, browser caches, and config folders for games and dev tools are often the real space hogs on C:. C-Slim links just those out to a data drive.
Store apps relocation
Move movable Microsoft Store apps to a data drive; for built-in apps offer whitelist-based trimming, and that trimming never runs automatically — you confirm each item.
Cache & TEMP drain
Drain package-manager caches and TEMP folders everywhere (including the copy already moved to the data drive): files only, directory structure preserved, and files written in the last day skipped so in-progress installs aren't disturbed.
Long-term protection
Take over newly installed software, point TEMP at the data drive, and register a scheduled inspection task so C: doesn't slowly fill back up. Every automated action is logged.
How it works
Four steps, fully reversible
Each step writes clearly to the log what it did and on what basis. If any step fails its check, the script stops instead of pushing blindly ahead.
Diagnose
Scan C: usage: Store apps, Program Files, AppData, user folders — see who is eating the space.
Copy
Copy the data to the data-drive target first; only after verification passes is the original touched. If verification fails, the original is left intact.
Relink
Re-point the Known Folder or create a directory junction at the original location, then read back to confirm the redirection actually took effect.
Wrap up
Tag the old copy as .orig and clean it on next reboot; rebuild the icon cache so desktop shortcuts return to normal.
Safety
Before deleting, prove it already exists elsewhere
This is the one non-negotiable principle of C-Slim. Both v1.5.x releases exist to do exactly this: turn "looks deletable" into "proven deletable".
- Verify before delete: the old backup is only renamed and queued for reboot cleanup after a byte-by-byte check confirms it already exists intact on the target drive.
- No skipped confirmations: steps that force-close programs in use or move data keep a bilingual confirmation prompt.
- Self-heals on interruption: if a migration is cut halfway, the next run detects the leftover state and rebuilds the links instead of stalling on "target already exists".
- No overwrite on conflict: if both sides have the same name but different content, the folder is skipped and C: is left untouched — never silently dropping files.
- Recycle Bin untouched: daily maintenance only drains TEMP by default; emptying the Recycle Bin needs an explicit flag to run.
- Paths from the environment: system directories are resolved from environment variables, so machines without Windows on C: stay safe too.
What a run log looks like
User folder target resolved: current location D:\Users\alilu Move Downloads: C:\Users\alilu\Downloads -> D:\Users\alilu\Downloads ... Verification failed, skipped Desktop (data intact, kept original on C:) Old C: copy tagged .orig, auto-removed after reboot
Every step leaves its reasoning behind: how the target was chosen, on what basis, and whether the result was to migrate or skip.
FAQ
Before you download, you probably wonder
Do I need to pay? Any bundled software?
Completely free, open source under the MIT license, no ads, no bundles, no online activation. The code is on GitHub — you can read it all before you use it.
Windows warns "unknown publisher" or SmartScreen blocks it — is that normal?
Yes. The scripts have no code-signing certificate, so Windows flags them as risky. Choose "More info → Run anyway". If you prefer, run it once in a VM or on a non-primary machine first.
Why must I run as administrator?
Creating directory junctions, editing the Known Folder registry, and registering scheduled tasks all need elevation. The script actually checks permissions at startup; without administrator rights it tells you clearly and stops — rather than failing halfway yet showing "done".
Will an interrupted migration (power loss, forced shutdown) lose data?
By design, no. Data is copied first, verified, then the path is switched; on interruption the old folder is still in place, and the next run detects the leftover state and self-heals by rebuilding the links. Still, back up important data before running, just to be safe.
My Windows isn't on C: — will it work?
Yes. System directories and Program Files are resolved from environment variables; the tool does not assume Windows is always installed on C:.
Can I undo it?
Yes. After migration the old folder stays as .orig until the next reboot; just change it back manually before that cleanup happens. A diagnostic script is also provided to show where each folder currently points.
Download
Download C-Slim v1.5.1
No install — unzip, then right-click and run as administrator. On first use, run the "diagnose" step once to see where your space went.
v1.5.1 · 2026-09-03
System requirements
- Windows 10 or Windows 11
- Administrator rights (launcher auto-requests elevation)
- Free space on target drive ≥ data to be moved
Read before you run
1) Back up important data; 2) If SmartScreen / Defender blocks it, choose "More info → Run anyway"; 3) After moving user folders you must sign out or reboot before File Explorer recognizes the new paths.
How to use
1. Download the ZIP and unzip anywhere 2. Right-click "①Run C-Slim.bat" → Run as administrator 3. From the menu pick 1 to run a diagnostic scan first 4. After confirming the list, pick A to migrate all at once 5. Restart when prompted after finishing
Prefer a GUI? Run Start-GUI.bat. Command-line users can use CLI-Menu.bat.