AtlasToolkit

Spine Atlas Toolkit - Extract, modify, and repack atlas sprites.

A GUI tool for working with Spine atlas files. View atlas regions, extract individual sprites, replace sprites with other image, and repack the atlas — all through a simple web-based interface powered by pywebview.

Usage

• Now, Web version is available here!
• You can use the pre-built executables or download stable version source code from Releases.
  • Windows is distributed as an installer (AtlasToolkit-Setup-x64.exe, per-user, no admin) plus a portable zip. The installed build updates itself silently in-app; the portable build links to the releases page.
  • One-time migration: builds made before the installer switch used the old single-exe auto-update and will report "asset not found" when checking for this release — download and run the new installer once manually.
• Or, clone the repository and run from source (in-development / unstable):

  git clone https://github.com/com55/AtlasToolkit.git
  cd AtlasToolkit

Setup & Run (If run from source)

Once you are inside the project directory, choose your preferred method:

• Using uv (Recommended)

  uv sync
  uv run python main.py

• Using pip

  pip install -r requirements.txt
  python main.py

  or

  pip install pillow pywebview requests
  python main.py

Features

• Atlas Preview — View the full atlas image with region overlays
• Region Extraction — Extract individual sprites or all regions at once
• Sprite Modification — Replace sprites with mod images, auto-expanding the canvas as needed
• Smart Repack — Repack all regions into an optimally-sized atlas after modification
• Drag & Drop — Load .atlas files by dragging them into the app; in Modify Mode, drop a .png image directly to apply it as a mod
• Copy to Clipboard — Right-click the preview image to copy it to clipboard (Extract Mode)
• Auto Format Conversion — Automatically converts LibGDX atlas format (xy/orig/offset) to the Spine format on load
• Multi-page Atlas — Supports atlas files that reference multiple page images
• File Association — Can be set as the default app for .atlas files; opening an atlas file directly will launch the app and load it automatically
• Update Notifications — Checks GitHub for new releases on startup and shows an in-app banner when an update is available
• Save Modified Atlas — Export updated .atlas, .png, and also copy .skel file if available

Acknowledgments

• Spine Atlas Format — Atlas format specification reference

Contributing

• Found a bug or have a suggestion? Please open an issue
• Pull requests are welcome!

License

This project is licensed under the MIT License — see the LICENSE file for details.

Disclaimer

This project is not affiliated with, endorsed by, or associated with Esoteric Software or the Spine runtime in any way. It was created for educational and personal use only.