Adding a new non-visual extension

Create a new folder in the custom extensions folder:

• Windows - C:\Users\username\AppData\Local\MuseScore\MuseScore4\extensions
• MacOS -
• Linux - $HOME/.local/share/MuseScore/MuseScore4/extensions

for example myquickstart.

In this folder, create a new file manifest.json
Fill out the manifest as follows:

{
    "uri": "musescore://extensions/myquickstart",
    "type": "macros",
    "title": "My quick start",
    "description": "This is a development extension for API research.",

    "path": "main.js"
}

Create a new file main.js
Fill out the manifest as follows:

function main() {
    api.log.info("called main from myquickstart")
    api.interactive.info("myquickstart", "called MAIN from myquickstart")
}

Launch MuseScore and enable your extension on the plugins page.
Open a project (some a score or create new) and call your extension from the plugins menu.
A dialog should be displayed with information from your extension.

Congratulations! You've created and added a new extension!

Adding a new visual extension

Create a new folder in the custom extensions folder:

• Windows - C:\Users\username\AppData\Local\MuseScore\MuseScore4\extensions
• MacOS -
• Linux - $HOME/.local/share/MuseScore/MuseScore4/extensions

for example myquickstart_v.

In this folder, create a new file manifest.json
Fill out the manifest as follows:

{
    "uri": "musescore://extensions/myquickstart_v",
    "type": "form",
    "title": "My quick start visual",
    "description": "This is a development extension for API research.",

    "path": "Main.qml"
}

Create a new file Main.qml
Fill out the manifest as follows:

import QtQuick

import MuseApi.Extensions
import MuseApi.Controls

ExtensionBlank {

    id: root

    implicitHeight: 400
    implicitWidth: 400

    color: api.theme.backgroundPrimaryColor

    StyledTextLabel {
        id: label1
        anchors.centerIn: parent
        text: "Quick start"
    }

    FlatButton {
        id: btn1
        anchors.top: label1.bottom
        anchors.topMargin: 8
        anchors.horizontalCenter: parent.horizontalCenter

        text: "Click me"

        onClicked: {
            api.interactive.info("Quick start", "Clicked on button")
        }
    }
}

Launch MuseScore and enable your extension on the plugins page.
Open a project (some a score or create new) and call your extension from the plugins menu.
A dialog with you form.

Congratulations! You've created and added a new visual extension!