Music Education.

A Score Music Composer
A-Score Music Composer is a music notation editor for Android from Philip Blandford. This successor to his earlier Chaconne app has several new features including the ability to work on individual parts.
https://play.google.com/store/apps/details?id=com.philblandford.ascore

abc
The abc format is especially popular for folk and traditional music. Its compact design makes it easy for people to type and read. Willem Vree's command-line abc2xml tool converts from abc to MusicXML files.
https://wim.vree.org/svgParse/abc2xml.html

Band in a Box
Band-in-a-Box from PG Music is one of the most popular automatic accompaniment applications, available for Windows and Mac. Version 2016 added support for MusicXML import and export.
https://www.pgmusic.com/


Calligra
Calligra Suite is a free integrated office suite for Linux systems. It includes the ability to read and write embedded MusicXML as part of compound office documents.
https://www.calligra.org/


DeluxeNote
DeluxeNote from Besuau is a music notation editor for Windows with a zoom-driven workflow. Version 1.0.4 added MusicXML export.
https://www.deluxenote.com/
https://www.besuau.com/


Ensemble Composer
Ensemble Composer from Lotuz Studio is a sheet music notation editing app for Android 2.2 and later.
https://play.google.com/store/apps/details?id=com.lotuz.musiccomposer


Free Clef
Free Clef is a lightweight open-source music notation editor for Windows and Linux that reads and writes MusicXML files. It includes user interfaces in both English and Portuguese
https://sourceforge.net/projects/freeclef/


Guitar Pro
Guitar Pro is a multitrack tablature editor for guitar, banjo and bass that runs on Windows. Besides writing scores, Guitar Pro helps guitarists improve their skills, compose, or simply accompany themselves. Version 5 added MusicXML support.
https://www.guitar-pro.com/


Harmony Assistant
Harmony Assistant is a computer-assisted composition and editing program from Myriad Software. It includes novel features such as an optional Virtual Singer module for singing lyrics as part of score playback. Version 9.0.5 added initial MusicXML support, with MusicXML 2.0 support added in Version 9.4.0. It is available for Windows, macOS, and Linux
https://www.myriad-online.com/en/products/harmony.htm
https://www.myriad-online.com/en/index.htm
https://www.myriad-online.com/en/products/virtualsinger.htm


Hyena
The Hyena cancer simulation program from Arizona Cancer Evolution Center simulates tumor growth and treatment in a MusicXML-encoded song
https://maleylabapplications.org/hyena/
https://cancer-insights.asu.edu/


JapoScore
JapoScore creates scores for traditional Japanese instruments such as shakuhachi, shinobue, koto, and shamisen from staff notation scores in MusicXML format. Layout editing and MusicXML export are also supported
https://fluteywinds.com/japoscore/#english


Komp
Komp is a music notation sketching app for iOS, optimized for the Apple Pencil.
https://kompapp.com/


libMusicXML
libMusicXML is a portable C++ library that supports conversion from and to an in-memory C++ format. This open source project is based on work conducted by the Grame Computer Music Research Laboratory. Version 3 supports the MusicXML 3.0 format
https://github.com/grame-cncm/libmusicxml/wiki
https://www.grame.fr/


MakeMusic CLoud
MakeMusic Cloud (formerly SmartMusic) is MakeMusic's interactive music education and practice software. MakeMusic Cloud runs on nearly any web-enabled device, including Chromebooks. The Compose tool allows teachers to create new music and import MusicXML files that can be assigned to students, supplementing the MakeMusic Cloud catalog. The Compose and Sight Reading Builder tools also include export to MusicXML files
https://www.smartmusic.com/


Nuendo
Nuendo is Steinberg's audio production environment for audio post, studio production and live recording. Nuendo added MusicXML import and export support in version 4 via the music notation features of the optional Nuendo Expansion Kit add-on package. The Nuendo Expansion Kit features were incorporated directly into Nuendo in version 8
https://www.steinberg.net/nuendo/
https://www.steinberg.net/


Obtiv Octava
Obtiv Octava is a Windows-based music notation editor. MusicXML support is available in version 8.4 of the SD25 and Standard editions
http://www.obtiv.de/


ProxyMusic
HervĂ© Bitteur's ProxyMusic library provides a binding between Java objects and a MusicXML 3.0 file, allowing marshalling and unmarshalling. It is designed to provide an easier way for Java programs that deal with symbolic music information to read and write MusicXML files. JAXB 2.0 is required
https://github.com/Audiveris/proxymusic
https://github.com/javaee/jaxb-v2


QuickScore Elite Level II
QuickScore Elite Level II is Sion Software's premier music composition product: an integrated 48-track scoring and sequencing program for Windows. MusicXML support was added in Version 10
http://www.sionsoft.com/qse2lit.html
http://www.sionsoft.com/


REAPER
REAPER from Cockos is a digital audio production application for Windows and macOS. Version 5.20 added a notation editor, followed by MusicXML export in version 5.22 and MusicXML import in version 5.23
https://www.reaper.fm/
https://www.cockos.com/


Scorio
Scorio is an online service for writing, sharing, and searching for music notation within a standard web browser. The Pro and Unlimited plans include MusicXML import and export, which were added in versions 1.0.1 and 1.0.8 respectively
https://www.scorio.com/


TablEdit
TablEdit is a program for creating, editing, printing and listening to tablature and standard notation for guitar and other fretted, stringed instruments. Version 2.64 added MusicXML support on Windows
https://www.tabledit.com/


UtaFormatix
UtaFormatix is a web app that allows you to convert back and forth between several popular singing synthesis formats. Version 3.0 included MusicXML export. MusicXML import was added in version 3.6
https://sdercolin.github.io/utaformatix3/


VocalEasel
VocalEasel is a simple lead sheet editor for macOS that uses MusicXML as its native format. It was developed by Matthias Neearcher as an editor and rehearsal tool for jazz vocalists
http://vocaleasel.sourceforge.net/