What is MusicXML? Opening and using .musicxml and .mxl files

MusicXML is a file format for sheet music. Almost every notation program can open and save it, so it is the usual way to move a score from one program to another. This app saves what it reads as MusicXML, and it can open MusicXML files too.

What MusicXML contains

A MusicXML file describes the score itself: parts and staves, clefs, key and time signatures, and every note with its pitch and length, plus rests, ties, slurs, articulations, dynamics, lyrics, and text. It is plain text in XML, so you can open it in a text editor. One measure looks like this:

<measure number="1">
  <attributes>
    <divisions>24</divisions>
    <key><fifths>0</fifths></key>
    <time><beats>4</beats><beat-type>4</beat-type></time>
    <clef><sign>G</sign><line>2</line></clef>
  </attributes>
  <note>
    <pitch><step>E</step><octave>4</octave></pitch>
    <duration>24</duration>
    <type>quarter</type>
  </note>
  <!-- … three more quarter notes: E, F, G -->
</measure>

Each note says which pitch it is (E in octave 4) and how long it lasts (duration, counted in divisions per quarter note). Because the file keeps the musical meaning, a program that opens it can lay out the score again, play it, transpose it, or change it.

MusicXML was designed by Michael Good at Recordare from 2000, and version 1.0 was released in 2004. MakeMusic took it over in 2011, and since 2015 it has been developed by the W3C Music Notation Community Group. The current version is 4.0 (2021).

MusicXML, MIDI, and PDF

Format	What it keeps	Good for
MusicXML	The notation: notes, rhythms, key, clefs, and markings, as written	Moving a score between notation programs; editing it later
MIDI	A performance: which key is pressed, when, how hard, for how long	Playing back on instruments and in music software; not for exact notation
PDF	A picture of the printed pages	Printing and reading; a program has to recognize the notes to use them (which is what this app does)

A MIDI file does not know whether a note is a G sharp or an A flat, whether a length is a dotted quarter or a quarter tied to an eighth, how notes are beamed, or which staff and voice a note belongs to, and its lengths are close to how long the keys were held. Turning MIDI into sheet music therefore always needs guessing. MusicXML keeps those details.

.musicxml, .mxl, and .xml

.musicxml: an uncompressed MusicXML file. This is what this app saves.
.mxl: compressed MusicXML (a zip file containing the score). Smaller; many programs save this by default.
.xml: older uncompressed files often use this more general extension.

This app opens all three. There are two ways to arrange the inside of a file, partwise (part by part) and timewise (measure by measure); notation programs save partwise, and that is the kind this app opens.

Programs that open MusicXML

Notation programs such as MuseScore Studio (free), Dorico, and Sibelius, as well as many score viewers and practice apps, can open and save MusicXML. How much of a score survives the move depends on the programs: notes and rhythms almost always come through; layout details and unusual markings may not.

From this app to MuseScore

Open and read a score in this app. Fix mistakes in Edit if needed (see fixing reading mistakes).
Press MusicXML. A .musicxml file is saved to your downloads.
In MuseScore, choose File → Open and select the file (or drag it onto the window).
Now you can correct what this app's editor cannot change (key, clefs, repeat signs), transpose, print, or export MIDI or audio.

The app reads notes, rests, clefs, key and time signatures, and some markings, but not lyrics, chord symbols, or dynamics. If you edited the notes in this app, slurs and articulations are not in the saved file.

From MuseScore to this app

To hear a score with the cursor of this app, or to use it on a computer without MuseScore, export it: in MuseScore choose File → Export and pick MusicXML (.musicxml or .mxl). Then choose or drop the file in this app. It opens at once, without reading, at the tempo written in the file.