Good old, easy composer for everyone
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Latest commit 2a64f39 Aug 16, 2014

Mario Sequencer

This is good old Mario Sequencer Web Edition. Works only on Chrome (at least for now).

Original software for Windows 95 by Anonymous in 2ch:

(News!) New version released. This time this supports one-chip HW Vocaloid Hatsune Miku and sings! If you have GAKKEN NSX-39, please try this version.

How to use

Try this link:

Also, here's GREAT music "NikoNiko suite" by Phenix.

Basically, What you see is what you get.

Select instruments with the buttons on the top of the screen. Most right button is not a instrument, but it is a end mark. If you select it, you can put the end mark on the score and play will stop there.

After selecting the instrument, put notes on the score as you like by left click. If you need to scroll the score to left or right, use the scroll range object.

If you want to delete the notes, select the eraser on the bottom of the screen, or just use right click on the target note.

The "Download" button will save your music as JSON file. Drag and drop your file and you can play it again.

You can use # and b(flat) for semitones. Just push Shift and Ctrl key while you left click.

This version lacks Undo implementation. Watch out, no Undo. So save many times.

This web app supports both JSON score files and MSQ files for Mario Sequencer for Windows. Just drag and drop MSQ files, they will be concatinated, and you can save it as one JSON file. Please number files such as file1.msq, file2.msq .... fileN.msq. If you want to change the tempo in the middle of the music, separate files, drag and drop all, then player will change the tempo automatically.

You can use this app without internet after download them all. I recommend you making local clone of this repository.

(Do you know Mario Composer file format? Or can you contribute that for me? :-)


There's some WEB API.

  • ?url="json or msq file URI"

You can download the score file by this.

  • ?auto="true or false"

You can play the music automatically by this.

  • ?mag="integer N > 0"

If you believe "The bigger, the better", Go for it!

  • ?SCORE="MSQ's sore data"

You can pass the score data by this.

Try these links for example.

Kerby's OP theme. Aunt Spoon (or Mrs.Pepper Pot)


This comes from good old SNES game, Mario Paint. Images and sounds belong to Nintendo.

All code is my original. Written in HTML + JavaScript. I declare the code in this web app as Public Domain. Only code, not images and sounds. Do what you want with my code. But I'm not responsible for anything, in any means.


Thank you all!