KeyLock Indicator

Know your lock keys. Without looking down.

A tiny Windows tray utility that shows Caps Lock, Num Lock and Scroll Lock on screen — the moment they change.

What it does

Your keyboard has no lights, or you never look at them. You start typing and suddenly EVERYTHING IS SHOUTING. KeyLock Indicator puts a small, clean card on your screen the instant a lock key changes, then gets out of the way.

It sits in the tray, needs no runtime, installs nothing, and stays invisible until it has something to tell you.

Screenshots

Dark theme	Light theme

The indicators

Every key gets its own mark, and on and off are different shapes — not just different colours — so the state stays readable if you cannot tell those colours apart. Below is the tray artwork, in the dark and light variants the app swaps between as your Windows theme changes.

Key	Dark taskbar		Light taskbar
Caps Lock	on	off	on	off
Num Lock	on	off	on	off
Scroll Lock	on	off	on	off

The card uses matching shapes, drawn in code as vector geometry so they stay sharp at any scale.

Features

• Instant on-screen display — a card with a soft shadow, drawn with Direct2D and composited with true per-pixel alpha
• Three looks — icon + text (the default), icon only, or a slim one-line bar
• Or keep it up — persistent badge mode parks a small live indicator at the spot you pick and leaves it there
• Never steals focus — keep typing; the caret does not move, and clicks pass straight through to whatever is underneath
• Follows your theme — light, dark, or whatever Windows is doing right now, switched live
• High contrast aware — turns on high contrast and the card goes fully opaque with system colours and a strong border, switched live
• Talks to screen readers — optional UI Automation announcements when a lock key changes, independent of whether the card is shown
• Sharp at any scale — per-monitor DPI aware (v2); the card is re-rendered at the scale of whichever monitor it appears on, never stretched
• Stays out of games — automatically suppressed in full-screen and presentation mode, badge mode included
• Per-app exceptions — name the apps that should never see the card; while one of them is in front, the OSD stays quiet
• Keyboard layout alerts — optional card when the active layout changes (TR-Q ↔ US and friends), with the real layout name from Windows
• Tunable — duration, opacity, size, position, and which keys to watch
• Multilingual — 25 languages, each listed under its own name, switched live without closing Settings
• Truly portable — drop a KeyLockIndicator.ini next to the exe and every setting lives in that file instead of the registry
• Take your settings with you — export and import the same .ini from the Settings window
• Feather-light — a single statically linked file, and it releases its GPU resources while idle

Feature matrix

Every item from the original wish list, with an honest verdict. ✅ done · ⚠️ partial · ❌ not implemented.

Full feature matrix (33 items)

#	Feature	Status	Notes
1	Caps Lock state	✅	Watched by default
2	Num Lock state	✅	Watched by default
3	Scroll Lock state	✅	Supported; off by default, since most keyboards no longer use it
4	Insert / overwrite mode	❌	Deliberately not shipped — the bit does not mean "overwrite". See the note below the table
5	On-screen display	✅	Direct2D card on a DirectComposition surface with per-pixel alpha
6	Nine-point position grid	✅	Corners, edges and centre; the edge margin applies on both axes
7	Free drag-and-drop placement	✅	"Pick on screen…"; stored as a ratio, so it survives resolution changes
8	Display duration setting	✅	800–4000 ms
9	Fade in / fade out animation	✅	Cubic-eased opacity and scale, driven by DirectComposition
10	OSD size setting	✅	75–150 %; text is re-rasterised at the target size, not stretched
11	OSD opacity setting	✅	60–100 %
12	Light / dark / system theme	✅	Follows Windows live, with a manual override
13	Icon-only view	✅	Small square card
14	Icon + text view	✅	The default
15	Minimal bar view	✅	Slim one-line bar, icon on the left
16	Persistent badge mode	✅	Off by default; stays on screen and tracks state live
17	Monitor choice (cursor / primary / all)	✅	"All" drives one composition chain per monitor
18	Per-application exclusion list	✅	Matched on the foreground executable name, case-insensitively
19	Full-screen detection and auto-hide	✅	SHQueryUserNotificationState; applies to badge mode too
20	Dynamic tray icon	✅	Reflects the chosen key's live state
21	Tray context menu	✅	Settings · Start with Windows · Pause · About · Exit, themed
22	Tray icon theme variants	✅	Separate light and dark artwork, swapped with the system theme
23	Start with Windows	✅	Run key, or windows.startupTask in the MSIX build; detects policy locks
24	Single-instance lock	✅	A second launch brings the running instance's Settings forward
25	Portable mode	✅	Drop a KeyLockIndicator.ini next to the exe; autostart still uses the registry
26	Global hotkey to summon the OSD	✅	Off by default (Ctrl+Alt+L); warns when the combination is already taken
27	Turkish / English interface	✅	Exceeded — 25 languages, switched live
28	Keyboard layout change indicator	✅	Off by default; resolves the real layout name, so TR-Q and TR-F are told apart
29	High contrast theme support	✅	System colours, opaque card, thicker border, no shadow; tracked live
30	Screen reader announcements	✅	Off by default; UiaRaiseNotificationEvent, DLL loaded on demand
31	Per-monitor DPI v2	✅	Declared in the manifest, with a runtime fallback
32	Import / export settings	✅	Same .ini format as portable mode; a corrupt file falls back per field
33	Low memory and idle CPU	⚠️	Idle is a fraction of a megabyte once the GPU chain is released. Not literally zero CPU — a 70 ms timer polls the key state. While the card is visible, memory is dominated by graphics driver heaps and exceeds the original target

On item 4. Reading VK_INSERT is easy; the problem is what the bit means. Windows keeps no global overwrite state — overwrite is each application's private editing mode. The bit is really "how many times Insert was pressed, mod 2", and Ctrl+Insert (copy) and Shift+Insert (paste) flip it too, so a user who copies and pastes would be told "Overwrite ON". Applications also start in insert mode no matter what the bit says. An indicator that is systematically wrong would undermine the three that are correct, so it was left out rather than shipped as a half-truth. The reasoning is written up in docs/DEVELOPMENT.md.

Languages

The interface ships in 25 languages, each listed under its own name. Pick one in Settings and it applies immediately — no restart, no reopening the window. Left on Automatic, it follows your Windows display language.

Čeština · Dansk · Deutsch · Ελληνικά · English · Español · Suomi · Français · Magyar · Italiano · 日本語 · 한국어 · Norsk bokmål · Nederlands · Polski · Português (Brasil) · Português (Portugal) · Română · Русский · Slovenčina · Svenska · Türkçe · Українська · 简体中文 · 繁體中文

Install

1. Download the latest ZIP from Releases
2. Unzip it anywhere
3. Run KeyLockIndicator.exe

That is the whole thing. It is portable — no installer, nothing left behind. Right-click the tray icon for Settings, or to start it with Windows.

Want it fully portable? Create an empty file called KeyLockIndicator.ini next to KeyLockIndicator.exe. Every setting is then read from and written to that file, so the whole app travels on a USB stick. The Settings window always tells you which of the two it is using. ("Start with Windows" still uses the registry — that is how Windows starts programs, and there is no file-based equivalent; unticking the box removes the entry again.)

Good to know

• The OSD cannot draw over the UAC prompt or the secure desktop. That is a Windows security boundary, not a bug.
• Some exclusive full-screen DirectX games may cover it.
• Inside a VM guest window, lock state can differ from the host.

Building from source, architecture and measurements: docs/DEVELOPMENT.md

MIT licensed · © 2026 ShadesOfDeath