MACM KeyBridge — Fix Broken Laptop Keys & Silence Annoying Ones (Windows)

For keyboards where some keys only work while another key is held down. Silences the key you keep pressed, remaps dead keys permanently, blocks the airplane-mode key and tells you whether the fault is Windows or the keyboard itself. 100% offline.

Download · Who is it for · Features · Quick start · How it works · Privacy · Documentación en español · miguelacm.es

🧩 Who is it for

KeyBridge opens with one question — "What is wrong with your keyboard?" — and takes you straight to the fix:

Your problem	What KeyBridge does	Needs the app running
Some keys only work while I hold another one	You wedge one key down and KeyBridge makes Windows ignore it completely	Yes
Some keys never work	A key you never use types for the broken one, system-wide	No
A key annoys me (Copilot, Windows key in games, Caps Lock, Insert…)	Makes it do nothing	Yes
Airplane mode turns on by accident	Blocks the keyboard's airplane-mode key, Wi-Fi untouched	No
I don't know what is wrong	Checks Windows and runs a 1-minute guided test with a verdict	—

The first case is the one that started this project: on many laptops with a cracked keyboard trace, a whole column of keys (for example 3, E, D and C) stops responding unless any other key is held down. The keyboard controller only scans that column while it is in continuous-scan mode, and it only enters that mode on a real, physical press. No program can press a key electrically for you — so KeyBridge takes the next best route: you hold the key with a wedge, and it makes that key completely invisible to Windows.

✨ Features

Silence keys

• Low-level keyboard hook (WH_KEYBOARD_LL) on a dedicated thread with its own message loop, reinstalled every 60 s (new hook installed before the old one is removed) so Windows never silently drops it.
• A silenced key produces nothing: no repeats, no menus, no shortcuts, no window-manager side effects, however long it stays held.
• Copilot key support — the hardware emits LWin + LShift + F23; KeyBridge buffers LWin for ~35 ms to recognise the sequence, so the real Windows key keeps working.
• Out-of-process engine — the hook lives in a windowless child process (--engine, JSON-lines IPC, respawned in 1 s if it dies). Windows stops delivering hook callbacks while the app's own WebView window has focus; measured 0 events before the split, 20/20 after.
• Per-key toggles, pause for 1/5/15/60 minutes or until resumed, and a global pause hotkey (Ctrl + Alt + B by default).

Swap keys (permanent)

• Writes the documented Scancode Map in HKLM\SYSTEM\CurrentControlSet\Control\Keyboard Layout, so a key you never use types the broken one with KeyBridge closed, for every user and on the sign-in screen.
• Asks for administrator rights once, needs one restart, and removes itself cleanly — byte-for-byte verified against the format Microsoft documents.
• Warns if another program already owns the map instead of silently overwriting it.

Airplane-mode key

• On most laptops Fn + F8 never reaches Windows as a key: it travels as a Wireless Radio Controls HID collection (HID_DEVICE_UP:0001_U:000C). No key blocker can stop it.
• KeyBridge disables exactly that collection through SetupAPI — the same as Disable device in Device Manager — and refuses to touch anything else. Keyboard, Wi-Fi, Bluetooth and the Windows airplane-mode toggle keep working.
• Remembers which devices it disabled, so it never re-enables something you disabled yourself, and detects when a Windows update switched it back on.

Diagnosis

• One-click checks for the usual software causes: Filter Keys, Sticky Keys, a foreign Scancode Map, third-party keyboard filter drivers, other remapping apps running, disabled keyboards and your BIOS version.
• Guided 2-step test: press the failing keys alone, then again while holding another key. You get a verdict — physical fault / no fault found / dead keys — with ranked next steps.
• Diagnostic report saved to your Desktop as plain text: Windows build, keyboards, checks and the keys you pressed during the test. Nothing is uploaded.

Key manual

• 28 bilingual key cards: what each key does on its own, what it does with Fn on a laptop, and a rating as a bridge key and as a sacrificial key — plus warnings (keys that open the BIOS or the boot menu if held at power-on, the one that kills your Wi-Fi).
• Recommended keys are one click away; the full manual only opens if you ask for it.

App

• Setup assistant, system tray, autostart as user or as administrator (scheduled task, works on battery), ES / EN, dark / light theme.
• Home states in plain sentences what is active right now — "F8 does nothing", "Fn + F8 still turns on airplane mode", "KeyBridge does not open by itself" — each with its own fix button.
• Fully reversible: per-feature undo, Undo all system changes in Settings, and the uninstaller runs the same cleanup automatically (skipped during updates).
• Lightweight — ~12 MB of RAM for the UI plus ~4 MB for the engine, no background CPU use, single portable .exe or a 2 MB installer.

Silence keys	Key manual

Swap keys	Diagnosis

🚀 Quick start

Install (users)

1. Download MACM.KeyBridge_x.y.z_x64-setup.exe from the latest release, or the portable .exe if you prefer not to install anything.
2. Optional — verify the download against SHA256SUMS.txt:

   Get-FileHash .\MACM.KeyBridge_1.0.0_x64-setup.exe -Algorithm SHA256

3. Run it. If Windows SmartScreen shows "Windows protected your PC" (common for new apps without a commercial code-signing certificate), click More info → Run anyway.

Requirements: Windows 10 (1809+) or 11, x64. WebView2 ships with Windows 11; the installer adds it on Windows 10 if missing.

Fix a keyboard whose keys need another key held (2 minutes)

1. Open KeyBridge and pick "Some keys only work while I hold another one".
2. Choose the key you will sacrifice — the Copilot key, F7, F8, F9 or Insert are the usual suspects. The built-in manual tells you what each one does first.
3. If you picked the airplane-mode key, block it too with the button that appears.
4. Wedge that key down for real: a folded piece of paper, a sliver of rubber, a drop of tape. This part is physical — software cannot press a key for you.
5. Type. Everything works, and the wedged key does nothing.
6. Turn on Open KeyBridge when the computer starts so it is there after every reboot.

Build from source (developers)

Requirements: Rust stable, Node.js 20+, Visual Studio Build Tools 2022 (C++ desktop workload), WebView2 Runtime.

npm install
npm run tauri dev      # development with hot reload
npm run tauri build    # portable .exe and NSIS installer in src-tauri/target/release/

Quality checks:

npx tsc --noEmit
cargo clippy --manifest-path src-tauri/Cargo.toml --all-targets -- -D warnings
cargo test --manifest-path src-tauri/Cargo.toml

🔧 How it works

macm-keybridge.exe                  UI process (Tauri 2 + React)
 └── macm-keybridge.exe --engine    engine process, no windows, ~4 MB
      └── WH_KEYBOARD_LL hook on its own thread with a message loop
 └── macm-keybridge.exe --radio     elevated helper: enables/disables the radio HID collection
 └── macm-keybridge.exe --remap     elevated helper: writes/clears the Scancode Map
 └── macm-keybridge.exe --cleanup   undoes everything (run by the uninstaller)

What software cannot do, stated plainly: it cannot close a broken circuit, cannot put the keyboard controller into continuous-scan mode, and cannot act on the sign-in screen or the UAC secure desktop. SendInput injects into Windows, not into the keyboard matrix. Everything KeyBridge does happens after the controller has already read the key.

Measurements, decisions and the full reasoning: docs/PROYECTO.md (Spanish).

🔒 Privacy

100% local · offline · no telemetry · no accounts · open source

• Sends no data anywhere. No analytics, crash reports, identifiers or updater.
• The UI cannot make network requests: its CSP only allows ipc:.
• The keyboard hook exists to block keys. Keystrokes are counted, never stored; the live key view used by the tester and the capture dialog is a short in-memory ring buffer that is dropped when you leave the screen, and the diagnostic report only contains what you pressed during the guided test, saved to your own Desktop.
• Your settings are readable JSON in %APPDATA%\es.miguelacm.keybridge\.

Details and how to verify it yourself: PRIVACY.md. Security policy: SECURITY.md.

🛠 Tech stack

• Tauri 2 — native shell, installer, tray
• Rust — hook engine, Win32 backend (windows-rs: WH_KEYBOARD_LL, SendInput, SetupAPI, registry, scheduled tasks), elevated helpers
• React 19 + TypeScript (strict) + Vite, Tailwind CSS 4
• Rust unit tests for the blocking logic and the Scancode Map layout; GitHub Actions release pipeline with SHA-256 checksums

⚠️ Honest limitations

• The held key has to be held physically. KeyBridge removes its side effects; it cannot create the press.
• Silencing keys needs KeyBridge running. Swapped keys and the airplane-mode block live in Windows and survive with it closed.
• Without administrator rights, silenced keys come back while an elevated window is in front (Task Manager, installers). Autostart as administrator fixes that.
• Swapping keys applies to every keyboard on the machine, including external ones, and needs a restart to apply or to undo.
• A damaged keyboard is still damaged. KeyBridge makes it usable; it does not repair it.

📄 License

MIT © 2026 Miguel Ángel Colorado Marin (MACM). Terms of use: TERMS.md. Want to contribute? CONTRIBUTING.md.

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Made by MACM · miguelacm.es · More free tools at miguelacm.es/tools