Remmina
Remmina is a remote desktop client written in GTK hosted on Gitlab [1]. It supports the following protocols: SSH, VNC, RDP, X2Go, HTTP(S)
Installation
- For VNC support install the libvncserver package.
- For SPICE support install the spice-gtk package.
- For RDP support, also install the optional freerdp or remmina-plugin-rdesktopAUR.
- Password saving depends on GNOME Keyring or KDE Wallet.
Note: If one of the protocols (e.g. RDP) is not available in the Remmina dropdown menu after installing the required package, make sure to completely quit Remmina first: run 
killall remmina. When you restart Remmina, the protocol should be available.Usage
To open previously saved connection profile you can do:
$ remmina --connect=~/.remmina/file-name.remmina
Depending on your setup, the dirname(1) might be ~/.config/remmina/, rather then ~/.remmina/.
Here is the script, which renames connection profile files basing on name= property to make it human readable:
#!/bin/bash
cd ~/.remmina/    # or ~/.config/remmina/ if appropriate
ls -1 *.remmina | while read a; do
       N=`grep '^name=' "$a" | cut -f2 -d=`;
       [ "$a" == "$N.remmina" ] || mv "$a" "$N".remmina;
done
To minimize to tray on startup, use the -i/--icon option.