Stave'n'Tabs - iOS and macOS notation and tablature editor with MIDI and MusicXML files support and chromatic...
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Aria Maestosa - Aria Maestosa is an open-source (GPL) midi tracker/editor.
music21 - Music21 is a Python-based toolkit for computer-aided musicology.
Chordsheet Maker - Create chord sheets or lead sheets quick and easily from your iPad. Add rhythms, endings, segno, codas and all what's necessary for your musicians to know what's your music about. Transcription made easy!
Harmony Assistant - Harmony Assistant is an unbeatable software for computer-assisted music composition and editing.