The app costs nothing, and the code is on GitHub. This is the license, as it is in the repository.
MIT License
Copyright 2026 Preston Landers
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
The name "Silverbox" and the icon and logo artwork (Silverbox/AppIcon.icon, Silverbox/AppIcon-Green.icon, and the AppIconAmber and AppIconGreen image sets) are not covered by this license. All rights reserved. If you distribute a modified version, give it a different name and icon.
The vendored decoders under Sources/CStbVorbis and Sources/CXmpLite keep their own licenses, in the LICENSE file beside each. The eXoDOS, eXoWin9x and other eXo collections are the work of the eXo team and are not part of this software.
What Silverbox uses
Two small C libraries are built into the app, each under its own license: stb_vorbis (public domain or MIT) decodes Ogg Vorbis menu music, and libxmp-lite (MIT) plays tracker modules. The app's Acknowledgments window shows both licenses.
The emulators are separate programs that you install yourself, each under its own license; Silverbox starts them and does not include them. The eXo collections are the work of the eXo team and are not part of Silverbox. This site shows GitHub's mark, from its Octicons (MIT License), to link to the repository.