CursorBloom

Shake your mouse to temporarily enlarge the Windows pointer—smoothly, sharply, and without changing your cursor scheme.

Download for Windows 11 · SHA-256 · MIT license

Watch the full-quality H.264 demo (MP4)

CursorBloom is a tiny native Windows 11 utility inspired by macOS “shake mouse pointer to locate.” Rapid back-and-forth motion replaces the visible pointer with one enlarged clone, keeps its hotspot aligned while it follows your movement, then settles smoothly back to normal.

Why CursorBloom

• One smooth pointer—no small original left underneath.
• High-density rendering for compatible standard Windows cursor schemes.
• Works with color, alpha-mask, and monochrome cursors.
• Horizontal, vertical, and diagonal shake recognition.
• Rejects straight swipes, single gaming flicks, slow movement, jitter, circular motion, drags, and movement while a mouse button is held.
• Pauses in fullscreen and presentation states by default.
• Refuses activation when Windows reports a hidden or suppressed cursor.
• Survives early-login and Explorer notification-area races by staying alive and retrying tray registration.
• No global mouse hook, injected component, service, network access, telemetry, or input synthesis.
• Portable x64 executable with no installer or administrator access.

Quick start

Requirements: Windows 11 on an x64 PC.

1. Download CursorBloom.exe and SHA256SUMS.txt from the latest release.

2. Verify the executable before running it:

   (Get-FileHash .\CursorBloom.exe -Algorithm SHA256).Hash
   Get-Content .\SHA256SUMS.txt

3. Run CursorBloom.exe. Its controls live in the notification area.

4. Shake the mouse left and right, vertically, or diagonally.

5. Use Start with Windows from the tray menu if you want it to launch automatically.

Important

CursorBloom is not currently code-signed. Windows may show an “Unknown publisher” or SmartScreen warning until the project builds reputation. Verify the SHA-256 checksum before choosing to run the executable.

The executable is portable. For a conventional per-user setup, place it at %LOCALAPPDATA%\CursorBloom\CursorBloom.exe before enabling Start with Windows. CursorBloom remains running if Windows launches it before Explorer's notification area is ready and retries the tray icon once per second until the shell accepts it. To remove that setup, run tools\uninstall.ps1; it validates the exact LocalAppData target before removing CursorBloom’s files and startup entry.

Tray controls

• Enabled
• Sensitivity: Low, Medium, High
• Maximum size: 2× through 6×
• Pause in fullscreen applications
• Start with Windows
• Pause for 15 minutes / Resume now
• About
• Exit

Settings are stored in %LOCALAPPDATA%\CursorBloom\settings.ini. Medium sensitivity and a 4× maximum are the defaults.

Games and fullscreen applications

CursorBloom uses runtime state rather than a blanket list of games:

• Fullscreen or presentation state: paused by default.
• Hidden or suppressed Windows cursor: cannot activate, including in a maximized window.
• Normal visible cursor in a game menu: remains available.
• Active effect followed by fullscreen entry or cursor disappearance: aborts and restores the native-pointer state immediately.

A rare game that draws its own cursor while still reporting an ordinary visible Windows cursor may need an explicit process exclusion. Add executable names to the diagnostic setting as a comma- or semicolon-separated list:

excluded_processes=example-game.exe;another-game.exe

How it works

CursorBloom receives background mouse movement through Windows Raw Input. A bounded 450 ms detector recognizes genuine reversals and rejects ordinary pointer movement. When triggered, it captures the active cursor and renders a small click-through layered window around its hotspot.

For static standard cursors, a larger native .cur frame is used only after the live cursor’s role, pixels, dimensions, and hotspot match exactly. Custom, animated, remote, ambiguous, or mismatched cursor sources stay on the live captured-raster fallback. The native pointer is restored before the clone is removed on every normal or fail-closed path.

See Architecture, Threat model, and Verification for the technical detail and evidence.

Build and test

The project is C++20/Win32 and uses pinned portable llvm-mingw 20260616 (Clang 22.1.8). It does not require Visual Studio or an installed Windows SDK.

After extracting the toolchain as toolchain\:

& .\build.ps1 -Configuration Test
& .\build.ps1 -Configuration Debug
& .\build.ps1 -Configuration Stress
& .\build.ps1 -Configuration Release

The public Windows CI downloads the exact archive in toolchain.lock, verifies its SHA-256, runs all tests, builds Release, and requires the checked-in release checksum to match. See Build and release.

Known limitations

• Application-defined and animated cursors may expose only their current raster frame, so no larger source detail exists to recover.
• Source-independent monochrome XOR/invert pixels use a visible white fallback because normal alpha layers cannot reproduce destination inversion.
• Fullscreen detection outside Windows-reported D3D/presentation states is necessarily heuristic.
• CursorBloom intentionally fails closed around secure desktop, unavailable Magnification cursor control, or an active fullscreen Magnifier transform.
• If Explorer's notification area remains unavailable indefinitely, CursorBloom keeps its core process active and retries the icon once per second; CursorBloom.exe --exit remains available as a clean escape path.

Security and privacy

CursorBloom has no network or telemetry code. Security reports should follow SECURITY.md. The exact 1.2.1 release passed unit, startup-retry, native-render stress, runtime-capability, import-surface, and Microsoft Defender checks recorded in Verification.

License

CursorBloom is available under the MIT License. Statically linked toolchain runtime notices are in THIRD_PARTY_NOTICES.md and licenses\.

CursorBloom is an independent project inspired by a familiar macOS accessibility behavior. It is not affiliated with or endorsed by Apple Inc.