Nightingale is a free audio player and web browser, based on the source code of the Songbird media player. As such, Nightingale’s engine is based on the Mozilla XULRunner with libraries such as the GStreamer and libtag multimedia framework providing support for markup and multimedia playback, among others. As the official Linux support was dropped by Songbird in April 2010, members of the Songbird community using Linux diverged and created the project. Unlike Songbird, which is primarily licensed under GPLv2 but includes artwork that is not freely distributable, Nightingale is free software, licensed under GPLv2, with portions under MPL and BSD licenses. Nightingale has not seen a new version since 2014 and most, if not all, Nightingale developers are no longer actively contributing to its development.
Users can add features and change Nightingale features by installing extensions. Extensions are similar to extensions for the Firefox browser and can be easily ported. Community-coded extensions are available on The Nightingale Addons.
The skins are called “feathers” in Nightingale, and give users and artists the ability to change the appearance of Nightingale via an extension that generates a default skin. By using CSS (and possibly XUL), and an image manipulation program such as Photoshop or GIMP, users are able to make Nightingale look like they want.