There are 2 repositories under transpose-chords topic.
jQuery plugin that lets you transpose chords in a plain text song
A python script transposing chords from one key to another.
A Python 3 package that provides a musical framework to analyse chords
Python module to transpose a song chords to any tone
Web application to display and edit songs with lyrics and chords.
Find proper spellings of chords and scales given starting note and type
You can transpose musical notations with this application.
ChordTransposer will take any chord and transpose it by any number of steps with the desired sharp or flat notation