Scale Degree for ChordWiki is a free Chrome add-on designed to enhance the functionality of the ChordWiki website by displaying relative scale degrees above the chords. This tool allows users to auto-detect the key or set it manually, making it versatile for various musical contexts. The scale degrees can be presented in either Roman or Arabic numerals, catering to different preferences among musicians and music theorists.

While the add-on significantly aids in understanding chord progressions, it is important to note that modulation support is not included. This limitation means that users should plan their chord arrangements accordingly, as the tool focuses solely on relative degrees within a single key. Overall, this add-on is a useful resource for those looking to deepen their musical analysis on ChordWiki.