ABC Desk Web runs in the page: the editor, the engraver and the piano all need JavaScript.
A browser workbench for ABC notation: the sheet, the transport and the parser in one page.
Anywhere
Outside the source
In the source
In the browser
A file can hold more than one tune, and the checker reads all of them, but the page is engraved one tune at a time: the sheet, the transport, the note highlighting and the keys all follow the first. Move another tune to the top of the file to work on it.
Your draft, the split of the panes and every setting are kept in this browser's localStorage; none of them leaves the machine. Clearing them makes the desk a first visit again — the example tune, the default theme, the panes where they start — and there is no way back.
Drop an .abc file on the source pane to open it, and Copy Share Link carries the tune in the address. Install the desk and it opens offline, samples and all.