Looks nice, but like others here we need something that can be self hosted or even better – run offline.

Somewhat related: does anyone know of any good components/libraries that can be embedded in a web page to let users interactively build SQL queries of reasonable complexity? By that I mean something that not only lets you pick columns and filter and maybe group things, but also do joins on other tables as well.

Edit: just to clarify, it doesn't have to be be visual only. In fact, something that lets you edit a query interactively either by visual components or actual SQL code is perfect, especially if it's bidirectional so that edits in the code also show in the UI and vice versa.