That kind of tool is indeed helpful. I wrote a kind of similar command line version that does a subset of what your's does in C around 1985 for my Mac, running in the terminal-like window my compiler's runtime provided for running command line programs.

Your's looks nicer :-)

Here's the output of mine for a C chord.

  C:  C E G
  <3>|-----|-----|-<5>-|-----|-----|-----|-----|-<1>-|-----|-----|-----|-<3>-|
     |-<1>-|-----|-----|-----|-<3>-|-----|-----|-<5>-|-----|-----|-----|-----|
  <5>|-----|-----|-----|-----|-<1>-|-----|-----|-----|-<3>-|-----|-----|-<5>-|
     |-----|-<3>-|-----|-----|-<5>-|-----|-----|-----|-----|-<1>-|-----|-----|
     |-----|-----|-<1>-|-----|-----|-----|-<3>-|-----|-----|-<5>-|-----|-----|
  <3>|-----|-----|-<5>-|-----|-----|-----|-----|-<1>-|-----|-----|-----|-<3>-|

and here it is if I toss in the narrow switch:

  C:  C E G
   3 |---|---|-5-|---|---|---|---|-1-|---|---|---|-3-|---|---|-5-|
     |-1-|---|---|---|-3-|---|---|-5-|---|---|---|---|-1-|---|---|
   5 |---|---|---|---|-1-|---|---|---|-3-|---|---|-5-|---|---|---|
     |---|-3-|---|---|-5-|---|---|---|---|-1-|---|---|---|-3-|---|
     |---|---|-1-|---|---|---|-3-|---|---|-5-|---|---|---|---|-1-|
   3 |---|---|-5-|---|---|---|---|-1-|---|---|---|-3-|---|---|-5-|

Here's the source [1], minimally updated to compile with current C compilers and to not depend on any quirks of the runtime of whatever C development system I was using on my Mac back then (Megamax C, I think).

I was pretty shaky on chord theory back then so not sure I'd trust it for fancy chords. I have no idea why the heck I made the D tuning flag tune both the 1st and 6th strings down to D. I'm 100% certain every piece of sheet music I had that called for for D tuning only wanted the 6th string tuned down.

[1] https://pastebin.com/HKyKWHip