Treejack is a tool to help you test the effectiveness of an information architecture. Use it to find out which categories are strong, which labels need tweaking and what tasks people are struggling with. Because you can upload an existing or proposed IA, and test with participants remotely, you get rapid feedback at a fraction of the cost of in-person testing.
Often, usability testing only reveals flaws with the interaction and interface elements. Treejack is a way to effectively test the quality of an information architecture itself.
Here is an example of a Treejack survey that a participant may complete: