XQuartz is a X11 server for macOS.

Setup on macOS 26 includes:

1. install it with Homebrew: brew install --cask xquartz;
2. in macOS system settings allow running it in background;
3. try to find optimal XQuartz settings for your goals (for me see below).

The best XQuartz settings for my purposes were:¹⁾

{
    "NSWindow Frame x11_apps" = "0 78 1512 871 0 0 1512 949 ";
    "NSWindow Frame x11_prefs" = "94 406 550 369 0 0 1512 949 ";
    SULastCheckTime = "2026-09-14 16:06:19 +0000";
    SUUpdateGroupIdentifier = 1688699947;
    "app_to_run" = "/opt/X11/bin/xterm";
    "apps_menu" =     (
                (
            "xfce4-terminal (server)",
            "ssh user@server xfce4-terminal",
            ""
        )
    );
    "cache_fonts" = 1;
    "done_xinit_check" = 1;
    "enable_iglx" = 0;
    "enable_key_equivalents" = 0;
    "login_shell" = "/bin/sh";
    "no_auth" = 0;
    "nolisten_tcp" = 0;
    "option_sends_alt" = 0;
    "startx_script" = "/opt/X11/bin/startx -- /opt/X11/bin/Xquartz";
    "sync_keymap" = 0;
}

This way i was able to change X11 keyboard settings using an own ~./Xmodmap.

defaults write org.xquartz.X11 app_to_run /usr/bin/true

I use XQuartz to run XFCE4 apps on a remote Linux server by using SSH:

ssh -Y "user@server" app

The following applications i run successfully so far:

• xterm
• xev
• xfig
• xpdf
• (GNU) emacs
• gimp
• thunar
• mx-tools
• xfce4-terminal
• xfce4-session (very slow, lot of warnings/errors)

On MX Linux server (which uses systemd at my site) i did:

• change /etc/hostname and /etc/hosts accordingly;
• install OpenSSH (SSH server);
• allow X11 forwarding in /etc/ssh/sshd_config:

  X11Forwarding yes
  X11UseLocalhost yes

• configure to start SSH daemon automatically:

  sudo systemctl start ssh.service

• change /etc/systemd/logind.conf (not to power-down my laptop on lid close):

  HandleLidSwitchExternalPower=ignore