Alternatives to TreeJack for IA/navigation testing? [on hold]

I'm planning to conduct some tree tests on a website's information architecture and navigation labels. (We're a small team with no dedicated UX colleagues.)

Does anyone know of any web app or other software alternatives to Optimal Workshop's TreeJack?

I'd really welcome some suggestions, please; it's the only tool I've found that seems to facilitate performing and analysis of tree tests. There must be something else out there!