Open Source & Acknowledgements

Kutio bundles several open-source and third-party command-line tools as subprocesses: 7-Zip (7zz), libarchive (bsdtar), Zstandard, XZ Utils, and RARLAB’s UnRAR. Nothing bundled is GPL. The full licence text for every component, alongside its pinned upstream version, travels with the app itself, in Help → Acknowledgements. The two components that carry a licence obligation beyond “ship the text” are detailed below.

7-Zip (7zz), version 26.02

Most of the code is GNU LGPL v2.1 or later. The RAR-decoding portion specifically carries LGPL with an added “unRAR license restriction,” which forbids using that code to build a RAR-compatible archiver or to re-create the RAR compression algorithm; it does not restrict using 7-Zip itself. A small amount of additional code is BSD-3-Clause or BSD-2-Clause. The LGPL obligation is satisfied by shipping the exact upstream licence text and version tag, and by invoking the unmodified official binary as a subprocess rather than linking or modifying it.

unrar (RARLAB), version 7.23, LicenseRef-UnRAR

This is RARLAB’s own custom freeware licence for the UnRAR utility, distinct from the separate RAR/WinRAR End User Licence Agreement that governs the rar binary (which Kutio does not bundle). Its exact required text, read directly from RARLAB’s own unrarsrc-7.2.7.tar.gz:

UnRAR - free utility for RAR archives
License for use and distribution of the FREE portable version

The source code of UnRAR utility is freeware. This means:

1. All copyrights to RAR and the utility UnRAR are exclusively owned by the author - Alexander Roshal.
2. UnRAR source code may be used in any software to handle RAR archives without limitations free of charge, but cannot be used to develop RAR (WinRAR) compatible archiver and to re-create RAR compression algorithm, which is proprietary. Distribution of modified UnRAR source code in separate form or as a part of other software is permitted, provided that full text of this paragraph is included in license, source code is available and license text does not indicate that it differs from this text.
3. The UnRAR utility may be freely distributed. It is allowed to distribute UnRAR inside of other software packages.
4. THE RAR ARCHIVER AND THE UnRAR UTILITY ARE DISTRIBUTED "AS IS". NO WARRANTY OF ANY KIND IS EXPRESSED OR IMPLIED. YOU USE AT YOUR OWN RISK. THE AUTHOR WILL NOT BE LIABLE FOR DATA LOSS, DAMAGES, LOSS OF PROFITS OR ANY OTHER KIND OF LOSS WHILE USING OR MISUSING THIS SOFTWARE.

                                            Alexander L. Roshal

Clause 2 is the reason RAR creation is permanently off the table for Kutio; it is not a missing feature or a future roadmap item.

Trademark caution. “RAR” and “WinRAR” are trademarks of win.rar GmbH. Nominative use (“Kutio extracts RAR archives”) is fine; Kutio does not use RAR’s or WinRAR’s logo or stylised wordmark anywhere on this site, and nothing here implies certification, partnership or endorsement by RARLAB or win.rar GmbH.

Other bundled components

libarchive (bsdtar), Zstandard and XZ Utils are also bundled as subprocesses. Their full licence texts, versions and copyright notices are reproduced in the app itself under Help → Acknowledgements; the source content for this page does not carry their exact version numbers, so they are not restated here to avoid getting a detail wrong.