This is not a duplicate of this SE post. Most questions of this sort center around an interview experience. I want questions that you might be genuinely interested in, even if they are not at all appropriate to ask during a job interview. If you have read the book Founders at Work, that is the kind of question I am talking about. So I guess, what would you ask if you were interviewing them? I am specially interested in questions that might give a possible future startup founder insight.