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Pratham
Pratham

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Windows AppData Junction Migrator: Free Up Your C Drive Without Breaking Apps

#productivity #automation #programming #opensource

Modern developer tools are storage monsters.

If you use tools like:

  • Cursor
  • VS Code
  • Docker
  • Node.js
  • AI/ML frameworks
  • Electron apps
  • Local LLM tools
  • Low storage SSD system
  • OR Any general apps

…you’ve probably noticed your C: drive slowly dying.

Even when apps are installed on another SSD, Windows still stores huge amounts of cache and configuration data inside:

C:\Users\<user>\AppData
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Over time this becomes a problem:

  • SSD fills up
  • Windows updates fail
  • Performance degrades
  • AI model caches explode
  • Docker eats tens of GB
  • Electron apps duplicate Chromium storage everywhere

I got tired of manually moving folders and creating symlinks.

So I built a safer automated PowerShell migration utility.

What This Tool Does

The utility safely moves heavy AppData folders from C: to another drive and replaces them with NTFS junctions.

Applications continue working normally.

Windows still thinks the folders exist on C:.

But the actual data lives elsewhere.

Example

Before:

C:\Users\prath\AppData\Local\Cursor
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After:

C:\Users\prath\AppData\Local\Cursor
 -> D:\APPDATA_REDIRECT\Cursor\Local\Cursor
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To the app:

  • nothing changed

To your SSD:

  • huge storage recovered

Why NTFS Junctions?

NTFS junctions are filesystem-level redirects built into Windows.

They are:

  • fast
  • transparent
  • stable
  • compatible with most Windows applications

Unlike shortcuts, applications treat junctions as real folders.

This makes them perfect for:

  • caches
  • package managers
  • AI model storage
  • extension folders
  • Electron app data
  • Docker layers

Features

Safe Migration Workflow

The script:

  1. scans folders
  2. verifies paths
  3. creates migration snapshots
  4. transfers data
  5. creates junctions
  6. validates success
  7. rolls back automatically on failure

Detects Existing Migrations

Already migrated folders are detected automatically:

[ALREADY MIGRATED]

[-] [Roaming]
    C:\Users\prath\AppData\Roaming\Cursor
    -> D:\APPDATA_REDIRECT\Cursor\Roaming\Cursor
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No duplicate work.

No accidental corruption.

Interactive Folder Selection

You choose exactly what gets migrated:

[1] [Local]
    C:\Users\prath\AppData\Local\Cursor

[2] [Roaming]
    C:\Users\prath\AppData\Roaming\Cursor
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Supports:

  • single selection
  • multiple selection
  • migrate all

Uses robocopy

Instead of basic file copy operations, the tool uses:

robocopy /E /MOVE
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Why this matters:

  • resilient transfers
  • retries
  • metadata preservation
  • large-folder reliability
  • safer than naive copy/delete

Automatic Rollback System

If anything fails:

  • junction creation
  • move operation
  • verification

…the script automatically restores the original folder.

This is critical when dealing with live application data.

Best Use Cases

This is especially useful for developers and AI engineers.

Cursor / VS Code

Extensions and AI indexes become massive over time.

Move:

AppData\Roaming\Cursor
AppData\Local\Cursor
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Docker

Docker Desktop can consume absurd amounts of SSD space.

Move:

AppData\Local\Docker
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Node.js

Package managers and caches grow endlessly.

Useful targets:

npm-cache
pnpm-store
yarn cache
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AI & ML Tools

Perfect for:

  • model downloads
  • embeddings
  • vector indexes
  • Hugging Face cache
  • Ollama storage
  • CUDA caches

How the Script Works

The workflow is designed to be defensive and recoverable.

Step 1 — Scan

The script searches:

AppData\Local
AppData\Roaming
AppData\LocalLow
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and even:

C:\Users\<user>\.<app>
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Step 2 — Snapshot

Before migration it records:

  • file count
  • destination
  • size
  • state

This enables recovery logic later.

Step 3 — Move Files

Using:

robocopy /MOVE
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The original directory is removed only after successful transfer.

Step 4 — Create Junction

PowerShell creates:

New-Item -ItemType Junction
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Applications continue working normally.

Step 5 — Verification

The script checks:

  • junction exists
  • target exists
  • transfer succeeded

If validation fails:

  • rollback begins automatically

Example Migration Output 

==================================================
STARTING MIGRATION
==================================================

Migrating:
    C:\Users\prath\AppData\Local\Cursor

[+] Files moved successfully

[+] Junction created
    C:\Users\prath\AppData\Local\Cursor
     ->
    D:\APPDATA_REDIRECT\Cursor\Local\Cursor
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Safety Notes

Do NOT migrate:

  • Windows system folders
  • Microsoft core directories
  • active system temp folders
  • random unknown services

Always:

  • close applications first
  • stop Docker if migrating Docker
  • stop AI servers before migration
  • run PowerShell as Administrator

The script already blocks some dangerous paths automatically.

Requirements

  • Windows
  • NTFS filesystem
  • PowerShell
  • Administrator privileges

Usage

Run PowerShell as Administrator:

powershell -ExecutionPolicy Bypass -File migration.ps1
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Real-World Impact

On my system this recovered:

  • tens of GB from Cursor
  • massive Docker cache usage
  • AI model storage clutter
  • Electron app duplication

Without breaking a single app.

This approach is especially useful on:

  • laptops with small SSDs
  • dev machines
  • AI workstations
  • dual-drive setups
  • systems using local LLMs

Final Thoughts

Windows AppData management becomes painful once you start working with modern development and AI tooling.

The problem isn’t installation size anymore.

It’s hidden storage growth.

NTFS junctions are one of the cleanest solutions available on Windows, and automating the process safely makes a huge difference.

If you’re constantly fighting low SSD space while doing development, AI, or Docker work — this approach can save your setup.

GitHub Gist Structure 

migration.ps1
README.md
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Windows AppData Junction Migrator Gist 🔗

License

MIT License

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pratham15541 profile image
Pratham •

If this helps you free up SSD space or clean your AppData chaos, drop a comment 👇