Musescore

MuseScore is a platform for writing, sharing and viewing sheet music, built around notation software that lets musicians compose and arrange scores. Users publish scores to the site's library, where others can browse, view and play back sheet music for a range of instruments and skill levels, from beginner exercises to full arrangements for ensembles and small groups.

Based in the United States, its ads.txt file lists 101 ad systems, 42 selling ad spots directly and 84 through resellers, split between direct and resold paths into its ad spots and pages.