RaspEX Build 170221 is is based on the software repositories of the Ubuntu 16.10 (Yakkety Yak) and Debian GNU/Linux 8.7 “Jessie” operating systems, as well as Linaro open source software for ARM SoCs. It uses the lightweight and fast LXDE desktop environment by default, along with the long-term supported Linux 4.4 kernel. The Linux kernel version included in RaspEX Build 170221 is kernel 4.4.49-exton-v7+, which Arne Exton injected with various extra patches for better hardware support. The new release also adds the Wicd network manager and replaces Chromium with the Mozilla Firefox web browser because it offers uses better YouTube support.