Free and open source software declarations

Salto XS4 Face Technologies uses free and open source software. Please see below for the open source packages used and their respective licenses. Information about which license texts and copyright notices refer to which source code can be taken directly from the source code we provide according to the written offer below.

Some Salto XS4 Face Technologies products work in conjunction with, and are distributed alongside, software developed by third parties, including software subject to the GNU General Public License ("GPL") versions 2. As applicable, the terms of the GPL, and information on obtaining access to the GPL code that builds into programs used by this product, are available to you in this document.

Under section 2 of the General Public License, our proprietary software is identifiably distinct from any GPL licensed programs. As a result, it is not permitted to distribute any version of our proprietary software without our express consent and it is not required to share the source code thereof.

At the request of the copyright holders of the GPL components, we refer to the following: Our programs are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License and the other applicable licenses for more details.

Written offer for GPL source code

Certain FOSS licenses require Salto XS4 Face Technologies to make available to recipients the source code corresponding to the FOSS binaries distributed under those licenses. This offer is exclusive to binaries distributed under the GPL license and does not extend to Salto XS4 Face Technologies's proprietary source code as distinct, separate software. Where such specific license terms entitle you to the source code of such software, this page contains direct links to the open source code used and is complete to the best of our knowledge. Salto XS4 Face Technologies will remedy, where possible, any omissions and provide to anyone upon written request via e-mail and/or traditional paper mail within three years after the distribution of the product by us the applicable source code via email or USB pen drive for a nominal cost to cover shipping and media charges as allowed under the GPL.

To make a formal request, visit our contact page.

Salto XS4 Face Technologies Free and Open Source Software (FOSS) Declaration and Licenses

There are 3 possible locations of distributed FOSS.

• XS4 Face Console: These libraries make up part of our online website and management portal. Any user that visits the site temporarily downloads the software and relevant license automatically. Retention is based on the user's own machine's caching settings.
• XS4 Face Server: Downloadable and installable onto an end-customer's own managed server, as well as installed on some Salto-provided servers.
• XS4 Face Device: Locked hardware that cannot be accessed by any user once produced, including Salto employees. Nonetheless, FOSS libraries and their respective licenses are installed and distributed along with these devices, as required by their respective licenses. The full, versioned list is in the XS4 Face Device declaration section below.

Apache-2

BSD-2

BSD-3

EPL

EPL-2

GPL

GPL-2

ISC

MIT

MPL-2

Python 2

Misc

XS4 Face Device declaration

Last updated: October 30, 2026

Applies to: XS4 Face release 26.5.11, which contains the XS4 Face Device application (door-scripts) version 1.10.105 and the XS4 Face Device base image built from commit 1b66f24 (image versions 1.31.6 to 1.32.1), on Raspberry Pi OS 11 "bullseye", arm64.

This section lists the free and open source software that ships on the XS4 Face Device. The same list, with full license texts, is installed on the device in /usr/share/licenses/door-scripts (device application) and /usr/share/licences/base (operating system).

Device application

The XS4 Face Device application runs as self-contained programs built with PyInstaller. Each program contains the Python runtime and the libraries below. The application uses pyca/cryptography, and the OpenSSL library built into it, to generate the device's RSA-2048 key pair and certificate signing requests.

Device operating system

The XS4 Face Device runs Raspberry Pi OS 11 "bullseye", which is based on Debian. The main packages are below. Debian package versions are shown as installed.

The full list of installed operating system packages is available on request through our contact page.