A lightweight, fast, and reliable keyboard layout switcher for Windows with text conversion between layouts.
Switch keyboard layouts with a single key tap (e.g. tap LCtrl for English, RCtrl for Ukrainian), and convert already-typed text from one layout to another with a hotkey — without losing the original clipboard.
Existing alternatives are either bloated keyloggers, abandoned, or feature-incomplete. LightSwitch aims to do one thing well:
- Lean — single ~2 MB executable, no dependencies, no installer required
- Fast — written in Rust, native Win32, sub-millisecond hook latency
- Reliable — no conflicts with system shortcuts (Ctrl+C, Ctrl+Shift, Win+Space all work)
- Privacy-respecting — no telemetry, no network, no logging
- Switch keyboard layouts via standalone modifier keys (tap LCtrl/RCtrl/LAlt/etc.) or key combinations (Ctrl+1, Shift+F1, etc.)
- Convert selected text (or entire text field) between layouts with a hotkey
- Cyclic conversion across all installed layouts (EN → UA → PL → EN)
- Automatic detection of the source layout based on the text
- System layout switches to match converted text — keep typing without manual switching
- Tray icon with settings window
- Per-user autostart (no admin rights required)
- Conflict detection in settings: cannot assign the same hotkey twice
Pre-release / MVP in development. Core functionality works but the project is not yet ready for general use.
Supports any keyboard layout installed in Windows — conversion tables are built dynamically at startup via ToUnicodeEx, so English, Ukrainian, Polish, German, Arabic, etc. all work out of the box. Multiple variants of the same language (e.g. English QWERTY vs. English Dvorak) are distinguished by their full HKL.
See docs/technical-specification.md for the full spec and roadmap.
- Apps without UI Automation support fall back to a clipboard-based flow. This flow can't read the caret position without selecting something first, so in editors with "smart copy" (e.g. Notepad++) pressing the "convert selection" hotkey with nothing explicitly selected may behave unexpectedly. Workaround: select the text explicitly before triggering conversion, or keep "Use UI Automation" enabled in settings (default) — most modern editors (Notepad on Win11, Word, VS Code, Chrome, Edge, most Electron apps) expose UIA and aren't affected.
- RAlt (AltGr), Win, and Fn keys cannot be used as hotkeys.
- No UAC elevation option for capturing keys in admin-level windows.
Requirements:
- Windows 10+ (x86-64)
- Rust toolchain (1.90+ recommended)
- MSVC build tools (installed automatically by
rustup)
git clone https://github.com/zergius-eggstream/lightswitch
cd lightswitch
cargo build --releaseThe resulting executable is at target/release/lightswitch.exe. It is fully standalone — copy it anywhere and run.
Just launch lightswitch.exe. The app starts hidden in the system tray.
- Right-click the tray icon → Settings to configure hotkeys
- Click each layout's hotkey field, then press the desired key (e.g. tap LCtrl)
- Configure the text conversion hotkey (e.g. Pause/Break)
- Optionally enable "Start with Windows"
- Save
Configuration is stored at %APPDATA%\LightSwitch\config.toml.
| Key | Notes |
|---|---|
| LCtrl, RCtrl | Distinguished left/right |
| LShift, RShift | Distinguished left/right |
| LAlt | Works as standalone |
| RAlt | Not supported (AltGr conflict on many layouts) |
| CapsLock | Works as a regular key |
| Function keys, letters, digits, etc. | Combined with Ctrl/Shift/Alt as needed |
| Win key | Not supported yet (Start menu conflict) |
| Fn key | Not visible to Windows API |
Notes when using modifiers as standalone hotkeys:
- LAlt — Windows may briefly highlight the menu bar in some apps when Alt is pressed alone. LightSwitch does not suppress this side effect.
- LShift / RShift — Windows accessibility shortcuts remain active: 5 quick Shift presses trigger Sticky Keys, holding Right Shift for 8 seconds triggers Filter Keys. Disable these in Windows Accessibility settings if they get in the way.
- Ctrl+Pause — Windows generates
VK_CANCELinstead ofVK_PAUSEfor this combo; LightSwitch normalizes this automatically.
TBD (likely MIT or Apache 2.0)
The project is in active development. Issues and pull requests welcome once the first release lands.