VirtBand

VirtBand is an online auto-arranger that runs entirely in the browser — a Band-in-a-Box style backing band for practice, songwriting and jamming, with nothing to install.

You write the song as a chord chart. Chords are typed in a compact shorthand that keeps entry fast and the sheet readable, including slash chords such as Am/C. Chords and whole bars can be copied, pasted and dragged to another place on the sheet, so reworking a chorus takes seconds. A song is built from several sections, with repeats, first and second endings, codas and the usual forms like AABA, so the chart follows the real structure of the tune rather than one flat loop.

Pick a style and VirtBand generates the accompaniment: drums, bass, piano, guitar and more, arranged across the form. The whole song can be transposed to any key, chosen on a circle of fifths that shows the key signature as you go, which makes moving a standard into a singer's key quick and easy to read.

Playback uses built-in SoundFont instrument banks, so it sounds like a band straight away without any extra downloads. A mixer gives every channel its own level, pan, reverb, chorus and tone, and instruments can be swapped on the fly while the music keeps playing, so you can audition a different piano or bass without stopping.

You can also write melodies. A piano roll and a notation view show the same part, with copy and paste, note-by-note editing, beams, triplets and rests, and a playhead that shows where the music has got to. Where a note can be spelled two ways, you choose which one the score shows — F sharp or G flat — instead of accepting whatever the program picks.

VirtBand can drive an external MIDI port instead of its own sampler, so the arrangement plays through Logic Pro, MainStage or any other DAW or sampler on your machine, using their sounds. Songs can also be exported as MIDI files and finished as a full arrangement elsewhere.

Finished tracks can be shared with someone by a link or published as a song page, and the site hosts a growing library of jazz standards you can open and play along with right away.