cwm is a very lighweight stacking window manager. It is part of OpenBSD's base system, but a portable version for other Unix-like systems exist.
cwm is keyboard driven for the most part. As per default it offers no titlebars or taskbars. There are default keybindings which are described in the man page, but you can configure cwm further in the file ~/.cwmrc
Website: https://man.openbsd.org/cwm.1