altoggle dayflower

Use this command to install altoggle with WinGet:

winget install --id=dayflower.altoggle -e

Switch the Windows IME with a solo press of a modifier key

altoggle

Switch the Windows IME with a solo press of a modifier key.

Press and release right Alt on its own → IME on
Press and release left Alt on its own → IME off
Alt with anything else → ordinary Alt, untouched

No new key to learn and no chord to hit: the two keys already under your thumbs become "start typing Japanese" and "stop typing Japanese", and they stay ordinary Alt for everything else.

The trade you are making

Whichever key you assign gives up its usual solo-press behaviour — Alt the menu bar, Win the start menu, Menu the context menu.

You get it back by holding the key. A press longer than the threshold (400ms by default) falls through to Windows untouched, so holding Alt still opens the menu bar. That is the escape hatch, and it is deliberate.

Either direction can also be set to (none) if you only want one of the two.

Requirements

Windows 10 or 11, 64-bit (x86_64)
A Japanese IME — Microsoft IME and Google Japanese Input are both known to work, across Notepad, Explorer, Chrome, VS Code and Store apps

altoggle sends the VK_IME_ON / VK_IME_OFF virtual keys. Under a US keyboard layout those keys do nothing, so with no Japanese IME active the app is inert rather than broken.

Install

Any of three ways. The first two also keep it up to date.

winget

winget install dayflower.altoggle

Scoop

scoop bucket add dayflower https://github.com/dayflower/scoop-bucket
scoop install dayflower/altoggle

By hand

Download the zip from the releases page and check the SHA256 if you like — it is published with each release.
Unblock it. Windows marks anything downloaded from the internet, and left marked the executable is treated as untrusted. Right-click the zip → Properties → tick Unblock → OK, before extracting.
Put altoggle.exe somewhere permanent — %LOCALAPPDATA%\Programs\altoggle\ is a reasonable home. There is no installer; the exe is the whole app.

Step 2 is the one the package managers spare you: they fetch the file themselves, so nothing arrives marked.

Then, however you installed it:

Run it. A tray icon appears. winget and Scoop both put altoggle on your PATH, and Scoop adds a start-menu entry.
To have it come back after a reboot, tick Start with Windows on the tray menu.

Autostart records the path the exe has right now. If you move or rename altoggle.exe afterwards, Windows will keep launching the old path; untick Start with Windows and tick it again to repoint it.

Quit altoggle from the tray before updating it. A running instance holds the executable open, and neither winget upgrade nor scoop update can replace a file that is in use.

Why Windows warns about it

altoggle is not code-signed, and it installs a low-level keyboard hook. Both are things SmartScreen and some antivirus heuristics react to, so expect a "Windows protected your PC" dialog (More info → Run anyway) on first launch.

That warning is about the absence of a certificate, not about anything the app was observed doing. What it actually does:

No network access at all. It opens no sockets and contacts nothing.
Writes exactly two things: %APPDATA%\altoggle\config.toml, and one value under HKCU\Software\Microsoft\Windows\CurrentVersion\Run — and that one only while Start with Windows is ticked.
Runs unelevated. It never asks for administrator rights.
The keyboard hook exists to see solo presses, which is the one thing that cannot be done any other way: deciding whether Alt was pressed alone means watching what comes after it. Nothing is recorded, stored or transmitted. The hook is crates/app/src/hook.rs and the whole source is here to read.

If you would rather not trust a binary from a stranger, build it yourself — see below. It takes one command.

Settings

Settings… on the tray menu opens a small dialog. It stays live while it is open, so you can change the threshold, press Apply, press the key, and feel whether the new value is right.

Trigger keys — either direction can be Alt, Ctrl, Shift or Win (left or right), the Menu key, or (none). Note that many Japanese laptops and JIS keyboards have no right Win key, and some have no Menu key; mixing sides (say left Win and right Alt) is fine.
Threshold — how short a press still counts as a solo press. Deliberate solo presses were measured up to 215ms and auto-repeat starts around 500ms, so useful values sit between roughly 250 and 500ms.
Show the IME state on the tray icon — off by default. When on, the tray icon shows a Latin a when the IME is off, a hiragana あ when it is on, and an asterisk when the foreground application will not say. It is off by default because reading the IME means asking the foreground application several times a second for as long as altoggle runs.
Dummy key (under Advanced) — the key injected to make a solo press stop looking solo, which is what stops Windows opening the menu bar. Leave it alone unless something in your setup reacts badly to 0x07.

The same values live in %APPDATA%\altoggle\config.toml, which is written with explanatory comments on first run. Editing it by hand works, but only takes effect at the next start — and the dialog rewrites the file whole when you save, so anything you add to it will not survive.

Reinstall hooks on the tray menu is there for the rare case where Windows drops the hook (it does so silently, and gives no way to ask). If solo presses suddenly stop working, try that before restarting the app.

Quitting

Quit on the tray menu. The release build has no console, so Ctrl+C does nothing — the tray menu is the way out.

Quitting releases every modifier key on the way, which matters here: altoggle suppresses the trigger key's release, and a modifier left logically held down would turn every later keystroke into a chord.

Uninstall

Untick Start with Windows on the tray menu.
Quit.
Remove the app: winget uninstall dayflower.altoggle, scoop uninstall altoggle, or delete altoggle.exe if you put it there yourself.
Delete the %APPDATA%\altoggle\ folder.

Steps 1 and 4 are yours whichever way you installed it. The Run entry and the config file are written by the app while it runs, and an uninstaller knows nothing about them. Beyond those two, that is everything: no installer state, no service, and nothing else in the registry.

Build from source

cargo build --release --bin altoggle

The result is target\release\altoggle.exe, a single self-contained executable — the icons are compiled into it and there are no DLLs to ship beyond the MSVC runtime.

One prerequisite is easy to miss: the build needs rc.exe from the Windows SDK, to compile the icon and version resources. A Rust MSVC toolchain that has link.exe but no SDK resource compiler fails here and nowhere else. Installing the Desktop development with C++ workload of Visual Studio Build Tools, with the Windows SDK component, is enough.

cargo build --release without --bin altoggle also builds three developer tools that are deliberately not distributed. Only altoggle.exe is the app.

License

MIT — see LICENSE.

altoggle

Switch the Windows IME with a solo press of a modifier key.

Press and release right Alt on its own → IME on
Press and release left Alt on its own → IME off
Alt with anything else → ordinary Alt, untouched

No new key to learn and no chord to hit: the two keys already under your thumbs become "start typing Japanese" and "stop typing Japanese", and they stay ordinary Alt for everything else.

The trade you are making

Whichever key you assign gives up its usual solo-press behaviour — Alt the menu bar, Win the start menu, Menu the context menu.

Either direction can also be set to (none) if you only want one of the two.

Requirements

Windows 10 or 11, 64-bit (x86_64)
A Japanese IME — Microsoft IME and Google Japanese Input are both known to work, across Notepad, Explorer, Chrome, VS Code and Store apps

altoggle sends the VK_IME_ON / VK_IME_OFF virtual keys. Under a US keyboard layout those keys do nothing, so with no Japanese IME active the app is inert rather than broken.

Install

Any of three ways. The first two also keep it up to date.

winget

winget install dayflower.altoggle

Scoop

scoop bucket add dayflower https://github.com/dayflower/scoop-bucket
scoop install dayflower/altoggle

By hand

Download the zip from the releases page and check the SHA256 if you like — it is published with each release.
Unblock it. Windows marks anything downloaded from the internet, and left marked the executable is treated as untrusted. Right-click the zip → Properties → tick Unblock → OK, before extracting.
Put altoggle.exe somewhere permanent — %LOCALAPPDATA%\Programs\altoggle\ is a reasonable home. There is no installer; the exe is the whole app.

Step 2 is the one the package managers spare you: they fetch the file themselves, so nothing arrives marked.

Then, however you installed it:

Run it. A tray icon appears. winget and Scoop both put altoggle on your PATH, and Scoop adds a start-menu entry.
To have it come back after a reboot, tick Start with Windows on the tray menu.

Quit altoggle from the tray before updating it. A running instance holds the executable open, and neither winget upgrade nor scoop update can replace a file that is in use.

Why Windows warns about it

That warning is about the absence of a certificate, not about anything the app was observed doing. What it actually does:

No network access at all. It opens no sockets and contacts nothing.
Writes exactly two things: %APPDATA%\altoggle\config.toml, and one value under HKCU\Software\Microsoft\Windows\CurrentVersion\Run — and that one only while Start with Windows is ticked.
Runs unelevated. It never asks for administrator rights.
The keyboard hook exists to see solo presses, which is the one thing that cannot be done any other way: deciding whether Alt was pressed alone means watching what comes after it. Nothing is recorded, stored or transmitted. The hook is crates/app/src/hook.rs and the whole source is here to read.

If you would rather not trust a binary from a stranger, build it yourself — see below. It takes one command.

Settings

Settings… on the tray menu opens a small dialog. It stays live while it is open, so you can change the threshold, press Apply, press the key, and feel whether the new value is right.

Trigger keys — either direction can be Alt, Ctrl, Shift or Win (left or right), the Menu key, or (none). Note that many Japanese laptops and JIS keyboards have no right Win key, and some have no Menu key; mixing sides (say left Win and right Alt) is fine.
Threshold — how short a press still counts as a solo press. Deliberate solo presses were measured up to 215ms and auto-repeat starts around 500ms, so useful values sit between roughly 250 and 500ms.
Show the IME state on the tray icon — off by default. When on, the tray icon shows a Latin a when the IME is off, a hiragana あ when it is on, and an asterisk when the foreground application will not say. It is off by default because reading the IME means asking the foreground application several times a second for as long as altoggle runs.
Dummy key (under Advanced) — the key injected to make a solo press stop looking solo, which is what stops Windows opening the menu bar. Leave it alone unless something in your setup reacts badly to 0x07.

Quitting

Quit on the tray menu. The release build has no console, so Ctrl+C does nothing — the tray menu is the way out.

Uninstall

Untick Start with Windows on the tray menu.
Quit.
Remove the app: winget uninstall dayflower.altoggle, scoop uninstall altoggle, or delete altoggle.exe if you put it there yourself.
Delete the %APPDATA%\altoggle\ folder.

Build from source

cargo build --release --bin altoggle

The result is target\release\altoggle.exe, a single self-contained executable — the icons are compiled into it and there are no DLLs to ship beyond the MSVC runtime.

cargo build --release without --bin altoggle also builds three developer tools that are deliberately not distributed. Only altoggle.exe is the app.

License

MIT — see LICENSE.

altoggle dayflower

README

altoggle

The trade you are making

Requirements

Install

Why Windows warns about it

Settings

Quitting

Uninstall

Build from source

License

altoggle dayflower

README

altoggle

The trade you are making

Requirements

Install

Why Windows warns about it

Settings

Quitting

Uninstall

Build from source

License