This is a super simple WordPress plugin that lists every table and its columns in your database so you can check to see if there's anything unexpected in there. It only lists things, there's no ability to change anything in your database and, in fact, no user input at all.

The page is in Tools and a user needs the 'list_users' capability to view it.

It might be an idea in the future to show all distinct meta_keys in wp_user_meta because sometimes people stash stuff in there, don't they?