A modern, cross-platform image editor compatible with Paint.NET 3.36 file format. KawaPaint is a clean rewrite built on a shared C#/SkiaSharp engine with Avalonia UI, running on Windows, Linux, Apple Silicon macOS, Android, and in the browser via WebAssembly.

Project Structure

• shared/ - Core engine (KawaPaint.Engine) and UI (KawaPaint.App), used by all platforms
• win/ - Windows desktop application (KawaPaint.Win)
• linux/ - Linux desktop application (KawaPaint.Linux)
• mac/ - Apple Silicon macOS desktop application (KawaPaint.Mac), with bundled JXL/JP2 codecs
• android/ - Android application (KawaPaint.Android), with touch/pen input and a compact workspace
• web/ - Browser application (KawaPaint.Web, WebAssembly/Avalonia.Browser)

Open KawaPaint.slnx to build any platform; all share the same engine and UI code.

Run the engine smoke tests and the headless UI regression checks with:

dotnet run --project shared/KawaPaint.Sandbox
dotnet run --project shared/KawaPaint.Sandbox -- --ui

The UI checks use an in-memory settings store and require no display server. Set KAWAPAINT_UI_SCREENSHOTS to an output directory to also save rendered layout screenshots.

Android on Apple Silicon

Install the Android workload, JDK 21, command-line SDK, API 36 platform and an ARM64 system image. The project recognizes the standard ~/Library/Android/sdk plus Homebrew's openjdk@21 path. Then:

dotnet build android/KawaPaint.Android.csproj -c Debug
adb install --no-incremental android/bin/Debug/net10.0-android/com.kawapaint.app-Signed.apk

Debug APKs embed their assemblies and can be installed directly. Desktop plugins and Git-backed history are disabled on Android; native JXL/JP2 are reported unavailable when no Android ABI pack is present.

Docker

The web image is served at / by default:

docker compose up

Set BASE_PATH when publishing it below a URL prefix. For example, this serves the app at http://localhost:8080/app/:

BASE_PATH=/app docker compose up

The reverse proxy should preserve that prefix when forwarding requests to the container.

Batch export

Named export presets are managed from File > Export > Manage Presets. Presets can resize or pad, choose codec settings, run a .kpscript, apply filename patterns, and emit caption/alt-text sidecars. The desktop executables also expose the same engine from the command line:

kawapaint --preset "Art Square" --in image.kwp --out-dir exported
kawapaint --script cleanup.kpscript --in-dir photos --pattern *.png --out-dir cleaned

Preset CLI runs read the normal KawaPaint settings.json; use --settings <path> to select a different settings file.

Publish artwork

Choose File > Publish Artwork to publish an export-preset rendering directly to Tumblr, DeviantArt, or a managed Facebook Page. The dialog supports Tumblr drafts/queueing, DeviantArt mature-content and gallery metadata, and Facebook Page captions and alt text.

Each service requires an API application. Register this desktop callback URL exactly: http://127.0.0.1:43817/callback/, then enter the application's client ID and secret in the publishing dialog. Secrets and OAuth tokens are stored in the operating system's credential vault, not in settings.json or image/project files. Facebook publishing targets Pages rather than personal profiles and may require Meta permission review. A new DeviantArt public/native client uses PKCE and therefore does not need a client secret; legacy confidential clients remain supported.

Instagram is export-only: the default presets include Instagram Square, Instagram Portrait 4x5, and Instagram Landscape. ArtStation publishing is not included because ArtStation does not offer an official public publishing API.

Tablet input and 3D reference layers

Pen pressure can control brush size, opacity, or both; inverted/eraser tips are recognized automatically. Touch input pans and pinch-zooms instead of painting. Configure this under Preferences > Drawing.

Choose File > Import 3D Reference to load an OBJ, glTF or GLB model, pose its yaw, pitch and roll in the live preview, and render it into a normal antialiased raster layer. The resulting pixels support the usual layer tools and undo/redo; the source model is not stored as a live scene.

Mail merge from CSV

Use the Dynamic Text / CSV Zone tool to place a non-destructive text area on a template. Its text may reference CSV columns—for example Binder — {StudentName} or {FirstName} {LastName}. Click a zone again to edit or delete it, then choose File > Export > Mail Merge from CSV. Select the CSV, an export preset and an output folder; KawaPaint creates one image per row while leaving the template unchanged. Comma-, semicolon- and tab-delimited files are accepted.

Credits

KawaPaint is maintained by Kawa.

Paint.NET - Based on Paint.NET 3.36 by Rick Brewster and contributors. See FORK.TXT for fork rationale.

Libraries

• SkiaSharp - 2D graphics rendering
• Avalonia - Cross-platform UI framework
• Avalonia.Controls.ColorPicker - Color picker control
• Avalonia.Themes.Fluent - Fluent design theme
• Avalonia.Fonts.Inter - Inter font package
• Avalonia.Browser - WebAssembly browser support

Icons

• Lucide - Toolbox, panel, and menu icons (shared/KawaPaint.App/Icons.cs) are adapted from the Lucide icon set, ISC License (with portions under the MIT-licensed Feather Icons this project forked from). See Lucide's license.

License

KawaPaint is licensed under the MIT License, consistent with Paint.NET 3.36. See LICENSE file for details.