Kumo puts common file actions in a radial menu on Windows. Start dragging files in File Explorer or on the desktop, tap Shift while holding the mouse button, then move to an action and release.
Images: convert PNG, JPEG, WebP, BMP and GIF (first frame) to PNG, JPEG, WebP, BMP or PDF; crop, rotate, and compress JPEG/WebP. PNG compression is lossless. Transparency is placed on white when saving to JPEG or BMP.
PDFs: convert pages to PNG or JPEG, combine images into a PDF, merge PDFs, split a PDF into one file per page, extract selected pages, or create a password-protected copy. PDF pages are rasterized at 150 DPI when converted to images.
Video, audio, HEIC, TIFF, Word documents, PDF text extraction and image resizing are not supported yet.
Kumo processes files locally and never uploads them. It does not overwrite originals; results are written as new files beside the source or to an output folder you choose. If automatic update checks are enabled, Kumo contacts GitHub to look for a newer version; that check does not send file contents or paths.
- Drag menu: drag files from File Explorer or the desktop, tap Shift, choose an action, then release.
- Keyboard: press Ctrl+Alt+K to open the menu for the current selection. The shortcut can be changed in Settings.
- Tray: open Kumo from the notification-area icon and select files.
Kumo never overwrites an original. By default it keeps originals; Settings can move them to the Recycle Bin after a successful operation. When an output name already exists, Kumo adds a number unless you choose to replace an older result.
Choose Release, Beta or Development in Settings. Beta includes beta and release-candidate builds; Development also includes alpha and dev builds. A source build has no update feed configured.
The menu opens over the current selection. Its actions depend on the selected files; this example shows the image actions available for one image.
Drag the crop frame's edges or corners, or choose a preset ratio such as 1:1, 4:3 or 16:9. Kumo saves the crop as a new image and leaves the original untouched.
Kumo is a C#/.NET 10 Windows desktop app. The UI is WPF; image and PDF operations are kept separate from the shell integration:
Kumo.Core— file and operation models, settings, and shared logic.Kumo.Operations— image processing with SkiaSharp and PDF operations with PDFsharp and Windows' PDF renderer.Kumo.Windows— Explorer, tray, hotkey, input and other Windows integration.Kumo.App— WPF interface and application lifecycle.
Builds target Windows 10 version 2004 or later. Release installers support x64 and ARM64; the per-user installer
does not need administrator rights. Building requires Windows and the .NET 10 SDK (10.0.400 or later, selected by
global.json).
dotnet build Kumo.slnx -c Release
dotnet test Kumo.slnx -c Release
dotnet run --project src/Kumo.AppCI runs formatting checks, version validation, build and tests on Windows. To prepare a release installer locally,
use tools/package-release.ps1; it requires NSIS 3 and builds self-contained installers for x64 and ARM64.
See CONTRIBUTING.md for setup and contribution guidance, and SECURITY.md for private vulnerability reports.
Kumo is licensed under the MIT License. See third-party notices for the licenses of components redistributed with the Windows installers.