Remmina is described as 'Open source client for Linux and BSD with support for RDP, VNC, and more, ideal for system administrators using remote desktops effectively' and is a very popular Remote Desktop tool in the network & admin category. There are more than 100 alternatives to Remmina for a variety of platforms, including Windows, Mac, Linux, Android and iPhone apps. The best Remmina alternative is TeamViewer. It's not free, so if you're looking for a free alternative, you could try TeamViewer or Termux. Other great apps like Remmina are Parsec, TightVNC, UltraVNC and Bananas Screen Sharing.