Lang Switcher

По-русски — переключатель раскладки клавиатуры, который исправляет слово, набранное не в той раскладке.

Lang Switcher fixes text typed in the wrong keyboard layout. You meant to type hello, but the Russian layout was on, so the screen shows руддщ. Press Pause/Break: the word becomes hello, and the window switches to the English layout. Press it again and you get the original back, exactly as you typed it. One key, no setup, nothing to learn.

A keyboard layout switcher for Windows 10 and 11 that fixes what is already typed instead of guessing while you type: a small tray program, free and open source, licensed under MIT OR Apache-2.0, with the interface in 66 languages.

Program page · Download · Keyboard layout converter · Questions and answers · No Pause/Break key on your laptop?

Status: version 1.4.4; the interface speaks 66 languages (see Languages). What changed in each version is in What's new below and on the Releases page.

How it works

• The word you just typed. Lang Switcher remembers the keys you pressed — the keys, not the text — and on Pause/Break retypes them in the other layout, erasing the wrong word first. A second press goes back, character for character, because the program keeps the keys themselves and never overwrites them with the result.
• Selected text. Select any text, press Pause/Break, and the selection is converted. The clipboard is put back exactly as it was afterwards, every format of it.
• Which layouts. By default, the two layouts you use most; you can name a pair or a cycle of several in the settings window.
• Where. Notepad, Word, browsers, messengers, Windows Terminal and the classic console. It also works in programs run as administrator. In password fields the program keeps no record of your keys at all.

Download and install

Releases are on the Releases page of this repository and on the download page of the site. The installer speaks the language of your Windows.

If the browser or Windows warns you. The program is signed with the author's own certificate, not one from a certification authority, and a new release is still downloaded rarely, so you will see warnings — this is expected:

• Edge: in Downloads, "…" → "Keep", then in the dialog "Delete ▾" → "Keep anyway".
• Chrome: "Download suspicious file".
• Windows may show "Windows protected your PC" — "More info" → "Run anyway". Then the yellow UAC prompt — "Yes".

Every window, step by step: Edge · Chrome · Opera · Yandex Browser · Firefox. You can check the file against the SHA-256 on its release page.

What the installer does with a certificate. Your Windows does not trust the author's certificate, so the installer creates one of its own on your computer, "Lang Switcher (local)": good for code signing only, not a certification authority, for 30 years. It signs the program with it, destroys the private key at once, and puts the public part into the computer's Trusted Root Certification Authorities. Uninstalling the program removes that certificate. If you would rather not have it, run LangSwitcher-setup.exe /NOLOCALCERT: you get a copy of the program without the certificate, which works everywhere except in programs run as administrator.

Requirements

Windows 10 or Windows 11, 64-bit. No runtime to install, no account, no internet needed to work.

Interface languages and keyboard layouts

The interface speaks 66 languages — 64 languages, Serbian and Uzbek in both of their scripts: English, Russian, Ukrainian, German, French, Spanish, Portuguese, Italian, Polish, Czech, Turkish, Greek, Hebrew, Arabic, Hindi, Bengali, Urdu, Punjabi, Marathi, Telugu, Tamil, Persian, Gujarati, Thai, Kannada, Odia, Malayalam, Uzbek (Latin and Cyrillic), Nepali, Assamese, Azerbaijani, Khmer, Kazakh, Serbian (Cyrillic and Latin), Uyghur, Bulgarian, Armenian, Lao, Belarusian, Tatar, Georgian, Macedonian, Vietnamese, Dutch, Romanian, Hungarian, Swedish, Albanian, Danish, Finnish, Croatian, Slovak, Norwegian Bokmål, Lithuanian, Slovenian, Bosnian, Latvian, Estonian, Welsh, Maltese, Icelandic, Luxembourgish, Māori and Norwegian Nynorsk; Hebrew, Arabic, Urdu, Persian and Uyghur read right to left. The language list of the settings puts the language of Windows, English, the languages of your keyboard layouts and Russian on top, and the rest by name.

Typing. The program converts between any two Windows keyboard layouts installed on your computer, except layouts with an IME (Chinese, Japanese, Korean), where a character is built from several keys in a candidate window. It was measured on the layouts of Windows 11 for 102 languages — 107 combinations of a language and a script (96, plus 11 smaller scripts): 16 Cyrillic, 45 Latin with letters of their own, 34 with a script of their own (Arabic, Hebrew, Greek, Armenian, Georgian, Thai, the Indian scripts and more) and Fula in ADLaM; then 11 smaller scripts (Cherokee, Javanese, Inuktitut in syllabics and in Latin letters, and others). Azerbaijani, Serbian, Mongolian, Central Atlas Tamazight and Inuktitut are each counted with two scripts.

The finer points:

• Letters a layout gives only with AltGr, dead keys (two in a row as well: BÉPO ´, ´, o is ő) and keys that print several characters at once (Arabic لا, Indian conjuncts) are converted the way Windows itself types them.
• Text in scripts with signs above and below the letters is erased and selected exactly: the program counts letters the way Windows does (Thai สวัสดี is 4 letters and 6 code points). In Notepad of Windows 11 the backspace method goes by the selection, like auto: that field loses or repeats characters of an insertion after Backspace, and it takes a typed Tamil consonant with its pulli (க்) off sometimes with one press, sometimes with two. The first press over a typed word selects it there by its position in the text, not by caret stops: one stop or three on the Tamil conjunct க்ஷ, and no count is right for both.
• When a key of the layout is ambiguous (Arabic 101: لا is one key, B, and also two, G and H) and the word was not typed just now, the program picks the reading that is more probable in the target language. It has letter statistics for English, French, Spanish and Russian, and since 1.2.0 for Arabic, Persian, Indonesian, Hindi, Tamil and Sinhala.
• The level of the right Ctrl of Canadian Multilingual Standard (the only layout of Windows with such a level, Japanese aside) converts into the same level of a layout that has it; a target layout without it does not take such a word, and the program sounds a refusal instead.
• In selected text the program cannot see CapsLock, and a character the target layout does not have is carried over as it is.

Where the letter statistics come from: public-domain books of Project Gutenberg (English, French, Spanish, Russian) and the Leipzig Corpora Collection, Universität Leipzig, licensed CC BY (the six languages of 1.2.0; the Sinhala corpus is drawn from Wikipedia, CC BY-SA). Only tables of letter frequencies are in the program, not the texts.

The hotkey

Pause/Break by default. In the settings window you can set another key, alone or with Ctrl, Alt and Shift (Ctrl+F12, Alt+Shift+K), or a double tap of Shift — two short taps in a row. No Pause key? Try Fn+Pause, a combination such as Ctrl+F12, CapsLock or the double Shift.

In the settings file %APPDATA%\Lang_Switcher\config.toml:

[hotkey]
key       = "F12"
modifiers = ["Ctrl"]    # any of "Ctrl", "Alt", "Shift"; [] for the key alone
trigger   = "press"     # press, or double_tap (with key = "Shift" only)

Privacy

Your keystrokes are never written to disk — not to the log, not to the settings, not to temporary files.

Once a day Lang Switcher reads a short news file from the author's site; it sends nothing about your computer. When a new version comes out, the program downloads it from the same site by itself, checks the author's signature and installs it while the computer is idle. A short notice by the tray icon tells you when it has been updated.

A message to the author from the wizard goes to the site only when you press Send yourself — exactly the text you saw before sending; a way to contact you is optional.

How it works, in detail:

• The news file is https://panda-pishet-kod.dev/langswitcher/news.toml — one GET request with no parameters. If it does not come, the next try is not before tomorrow. Letters and news from it can be turned off in the settings file ([letters] feed = false), and, after the first letter of the feed but not earlier than 90 days after the first start, in the "From the author" window as well.
• Updates are installed not by the program itself but by a separate file without a window, LangSwitcherUpdate.exe, a scheduled task "Lang Switcher Update" running as the system. It takes the installer only from the /langswitcher/files/ folder of the same site; its size and SHA-256 must match the ones signed in the news file, and its version must be newer than yours. If the new version does not start, the previous one comes back.
• A message from the wizard is one POST request to https://panda-pishet-kod.dev/langswitcher/feedback, sent only when you press Send or Retry. It carries the text of the message as it stands in the window, the language of the interface, the kind of message (a problem or a suggestion), the version of the program, your contact if you typed one, and a random number of the request so that the site does not file a repeat twice. The program waits for the answer no longer than 15 seconds. If the site does not answer, the wizard offers to send the same text by email to [email protected] or to save it to a file.

There is no other network activity. The details are in section 9 of the specification (in Russian).

What's new

New in 1.4.4: if the bare grave key is assigned as the language switcher in Windows, as is common in Thailand, the program treats it as a switcher: the word typed after it converts correctly, the text around it stays intact, and a second press of the hotkey still brings the original back (it used to count as a typed character); in Ukrainian, Arabic, Persian and Thai the name of the program and the download button open the pages of the site in that language; the numeral in the Arabic line under the news is corrected. Version 1.4.2: the interface quotes in the marks of its language (English, German, Czech, Polish, Turkish, Portuguese); in Notepad of Windows 11 the backspace method goes by the selection, like auto, and a typed word is selected by its position, so a Tamil word no longer takes the space before it or leaves a piece of itself behind; the pair of the configuration file accepts the identifier of a variant of a language (0x00020422), a layout that is not there is refused with a line in the journal, and the pair looks at the first 64 layouts of the session; the emergency chord Ctrl+Alt+Shift+F12 no longer reaches the window under it. Version 1.4.1: a letter the target layout builds from two dead keys in a row is built the way Windows builds it (French BÉPO ´, ´, o is ő); a word typed on the level of the right Ctrl of Canadian Multilingual Standard converts into the same level of a layout that has it; in Notepad with Tamil 99 the replacement no longer lands after the word with nothing erased. Version 1.4.0 added 22 interface languages, 1.3.0 another 30; 1.2.0 brought the Send button of the "Write to the author" wizard and the letter statistics of six more languages. Since 1.0.0 the program updates itself.

Reporting a problem or an idea

The tray menu → "Write to the author…" opens a short wizard: it collects what is useful (only what you leave ticked), shows you the whole text, and sends it with Send. Or open an issue in Issues — in English or Russian.

Building from source

cargo build --release

Before a release build:

cargo clippy -- -D warnings

cargo test

The tests are tied to the developer's machine (exactly two layouts, Russian and US) and are not expected to pass unchanged elsewhere; this is a decision of the project, not a defect. The release scripts, the installer and the signing are described in README.ru.md and in the specification SPEC.md; like the other documents of the project, they are in Russian.

License and authorship

Copyright © 2026 Panda Koder

The source code is available under either of MIT or Apache-2.0, at your option: LICENSE-MIT, LICENSE-APACHE. Contributions are accepted under CLA.md; see CONTRIBUTING.md.