dtach is described as 'tiny program that emulates the detach feature of screen, allowing you to run a program in an environment that is protected from the controlling terminal and attach to it later' and is a terminal emulator in the os & utilities category. There are six alternatives to dtach for Linux, Mac, BSD, Cygwin and Xfce. The best alternative is tmux, which is both free and Open Source. Other great apps like dtach are GNU Screen, Wemux, mtm and abduco.
dtach is mainly a Terminal Emulator but alternatives to it may also be Shells or Window Managers. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of dtach.
tmux is a terminal multiplexer: it enables a number of terminals (or windows), each running a separate program, to be created, accessed, and controlled from a single screen. tmux may be detached from a screen and continue running in the background, then later reattached.
Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each virtual terminal provides the functions of the DEC VT100 terminal and, in addition, several control functions from the ANSI X3.
abduco provides session management i.e. it allows programs to be run independently from their controlling terminal. That is programs can be detached - run in the background - and then later reattached.
Zellij is a terminal workspace. It has the base functionality of a terminal multiplexer (similar to tmux or screen) but includes many built-in features that would allow users to extend it and create their own personalized environment.