Turn your Caps Lock into a system-wide vim-style navigation layer — without losing the original Caps Lock function.

Caps Lock sits on the home row but does almost nothing. HyperCapslock remaps it to F18 (a key that doesn't physically exist on any keyboard), then intercepts F18 + other key combos at the OS level to simulate navigation, editing, input switching, and shell commands.

Because F18 isn't a real modifier (not Cmd, Ctrl, Shift, or Alt), it stacks with all of them for free:

No extra configuration. System modifiers pass through naturally.

If you just tap Caps Lock and release without pressing anything else, it still toggles Caps Lock on/off as normal.

All mappings are customizable through the GUI. These are the defaults:

Caps + Shift + [Key] can be bound to run arbitrary shell commands via the GUI.

brew install --cask XueshiQiao/tap/hypercapslock

Or download the .dmg from GitHub Releases.

The app needs Accessibility and Input Monitoring permissions: System Settings → Privacy & Security → Accessibility / Input Monitoring

Karabiner-Elements is a powerful tool with 21k+ stars, and I used it for years. But for the specific use case of "Caps Lock as a navigation layer":

• Config complexity — Karabiner requires hand-editing JSON for non-trivial remaps. HyperCapslock has a point-and-click GUI.
• Footprint — Karabiner installs a kernel extension and multiple background processes. HyperCapslock is a single ~5 MB Tauri app.
• The modifier problem — Karabiner typically maps Caps Lock to a real modifier combo (e.g., Ctrl+Shift+Cmd+Opt). This "hyper key" approach works but can conflict with existing shortcuts. HyperCapslock maps to F18, which conflicts with nothing and naturally stacks with real modifiers.

If you need Karabiner's full power (per-app rules, mouse remapping, device-specific profiles), use Karabiner. If you mainly want vim navigation everywhere with minimal setup, this might be a simpler path.

CapsLock is remapped to F18 via hidutil at the OS level. The app then installs a CGEventTap at the HID level — a system-wide event tap that intercepts key events before any application sees them.

When F18 is held and another key is pressed, the app swallows the original event and injects the remapped key (e.g., arrow key) into the system input stream. Injected events carry a flag to prevent feedback loops.

State tracking uses lock-free atomics (AtomicBool, AtomicU64) for zero-overhead thread safety. The hook callback does minimal work — integer comparisons and early returns — to avoid introducing input lag.

For the full technical deep-dive, see how_does_it_work.md.

• Tauri 2 (Rust backend + React/TypeScript frontend)
• CoreGraphics CGEventTap + hidutil for F18 remap
• ~5 MB binary, single process

• macOS 12+
• Node.js (v16+)
• Rust (latest stable)

git clone https://github.com/XueshiQiao/HyperCapslock.git
cd HyperCapslock
npm install
npm run tauri dev

npm run tauri build

• Hotkeys stop working: Logs are written to /tmp/hypercapslock-macos.log. Try removing and re-adding the app in Accessibility permissions, then relaunch.
• Gaming Mode: Pause/resume via the menu bar icon to temporarily disable all remapping.

GPL v3.0 — see LICENSE.