Summary of alternative abc converters mentioned above and on The Session forum

abcjs
https://www.abcjs.net/abcjs-editor.html
on
https://www.abcjs.net/

Colin Hume's converter
https://colinhume.com/Music.aspx

DrawTheDots abcjs quick editor
https://editor.drawthedots.com/
on
https://drawthedots.com/

Folk Tab
https://folktab.com/edit/abc

Jens Wollschläger's ABC-Transposer   
http://www.franziskaludwig.de/abctransposer/

Montreal Session Tunebook
https://www.montrealsession.ca/editor.php

The Session - ABC Editor
https://thesession.org/tunes/editor