FuckCapsLock

Caps Lock is a vestigial organ — this app permanently disables it until you terminate the app.

A lightweight Windows background utility that hooks the keyboard at the system level and swallows the Caps Lock keypress before it reaches any window. Runs silently in the system tray, auto-starts with Windows, and only stops blocking Caps Lock when you explicitly exit via the tray menu.

How It Works

FuckCapsLock installs a low-level Windows keyboard hook (WH_KEYBOARD_LL — SetWindowsHookEx). Every keypress passes through this hook before any application sees it. The hook inspects the virtual-key code and, if it matches VK_CAPITAL (0x14), returns 1 (blocked) without calling CallNextHookEx. All other keys pass through normally.

No driver, no service, no admin rights required. It's a single-user-mode userland hook that runs in your session's context.

Usage

Run fuckcapslock.exe — it minimizes to the system tray immediately
Caps Lock is now permanently disabled — pressing it does nothing
To restore Caps Lock, right-click the tray icon and select Exit
The app registers itself in HKCU\Software\Microsoft\Windows\CurrentVersion\Run for auto-start on next boot

Build

dotnet publish -c Release -r win-x64 --self-contained

Output: bin/Release/net10.0/win-x64/publish/fuckcapslock.exe

A pre-built self-contained exe is also available in the out/ directory.

Requirements

Windows x64 (x86-64 processor)
No .NET runtime required for the self-contained build

Tested on Windows 11. Should work on Windows 10 and 8 as well.

System Calls Reference

Every Win32 API and registry call the application makes, for auditability:

API / Call	Module	Purpose	Risk
`SetWindowsHookEx(WH_KEYBOARD_LL, ...)`	user32.dll	Install low-level keyboard hook	Blocks only VK_CAPITAL
`UnhookWindowsHookEx(...)`	user32.dll	Remove hook on exit	Cleanup — no data sent
`CallNextHookEx(...)`	user32.dll	Pass unchecked keys to next hook	Normal keyboard passthrough
`GetModuleHandle(...)`	kernel32.dll	Get module handle for hook install	Standard hook setup
`Registry.CurrentUser\...\Run`	Microsoft.Win32	Register for auto-start on boot	Writes only its own exe path
`NotifyIcon`	System.Windows.Forms	System tray icon	Visual indicator only — no data
`Application.Run(...)`	System.Windows.Forms	Message loop	Keeps process alive
`Mutex("Global\FuckCapsLock")`	System.Threading	Prevent duplicate instances	Singleton pattern

No network calls, no filesystem reads/writes (beyond registry auto-start), no process injection, no DLL sideloading, no keylogging. The only key intercepted is Caps Lock (0x14), which is swallowed and never forwarded.

Background

Caps Lock was designed for typewriters where holding Shift was physically strenuous. On modern keyboards it serves no purpose — it toggles a mode that accidentally inverts case for entire sentences. Every major OS has considered removing it (Apple briefly experimented, Chromebooks replaced it with Search, IBM's Model M had a removable keycap). This utility exists so you don't have to rip the keycap off your laptop.

License

MIT License — see LICENSE.

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