If you're on a mac, try monodraw. It's discontinued, but it's cheap and works great (it's basically a full featured diagramming app – with text output).
I really liked monodraw but am reluctant to pay for a license now that it's more or less been abandoned. I still like it, but only bought a copy for work at megacorp and foolishly didn't put it in my name.
I'm not sure I understand this attitude. It's a pitty it failed commercially. But it's a great app that only costs a tenner and works well (probably way better than any available alternative). And it can "save" as text, so it's not like you're going to lose all your work.
Surely, a good investment for anyone above minimum wage who does ascii art periodically on a mac?
What makes you think it's abandoned? The author is active on Twitter, the last update for dark mode was in May 2019 and I don't see any show stopper bugs or crashes on Catalina. Small utilities like this don't need an update every month. I bought it a while ago because
1) It's very cheap and a great show case for a small niche Mac app that's both beautiful and works well
2) The two times per year I use it, it's already worth it and fun to play around with.
The last blog entry I saw was that it's been put into maintenance mode. If your interest has fizzled but you still want to keep the product out there, that's a great use case for open source. I'm just not that inclined to pay for something that's not being actively developed.
Obviously at some point last year it got a new feature (yay). That speaks to the app itself being feature incomplete.
https://www.gnu.org/software/emacs/manual/html_node/emacs/Ba...
Here is a good summary:
http://ergoemacs.org/emacs/emacs_ascii_diagram.html