[nicklaf]

Thanks for pointing this out--it brought my attention to the author's Irmin backend, based on the browser's implementation of IndexedDB:

https://github.com/talex5/irmin-indexeddb

That said, trying out this demo [1] of Cuekeeper gives an IndexedDB error message on Firefox 40.0.3 on Linux; perhaps IndexedDB is somehow not enabled.

[1] http://roscidus.com/blog/cuekeeper/