What is MellowPlayer?
MellowPlayer is a cloud music integration for desktop!
It supports multiple mainstream music streaming services (like Spotify, Deezer, Google Music Play, Soundcloud, Mixcloud.....). The visual look of the services are the same as their browser version, and the application provides integration with the desktop (media keys support, global shortcuts, notifications, etc.).
The application is open source, and supports plugins for adding new streaming services.
According to their GitLab repository, it says that it is no longer maintained.