access permission

First off, I'd just like to say what a great job you have done. I have been looking for something like Sidewise on Chrome as I make extensive use of tree style tabs on ff and the lack of a decent alternative was stopping me (until now) from making more use of Chrome.

My question is regrading access permissions. Why does Sidewise require permission to my data on all websites?

Thanks

(I'm also currently unemployed so have not donated yet but I fully intend to when I am back in work)