There are not many other ascii diagramming tools

(ascii to diagram)

Typogram https://code.sgo.to/typograms/#installation

Markdeep https://casual-effects.com/markdeep/

svg bob editors https://ivanceras.github.io/bob-editor/ https://mbarkhau.github.io/asciigrid/

Ditaa https://ditaa.sourceforge.net/

Goat https://github.com/blampe/goat

Protocol https://www.luismg.com/protocol/

(dsl to ascii)

https://diagon.arthursonzogni.com/#Sequence

https://textart.io/sequence

https://weidagang.github.io/text-diagram/

https://diagwiz.io/playground/

There is another, related class of tools, and that is graphical editors of the Unicode box-drawing characters:

https://github.com/lewish/asciiflow

https://github.com/tbanel/uniline/

Or, less ergonomically, the general rectangle-editing commands built into more powerful code editors e.g. Emacs.

With these, simple but fairly pretty box+line+text diagrams can be inlined with your source code comments. This unification may help in the perennial struggle to keep software architecture and source code reality in sync.

https://d2lang.com/ is really nice.

Also I used to use https://swimlanes.io/ before d2.

Also,

https://pikchr.org/

Needs to have a '+' and the elbows and T intersections.