><i>In those cases, what do you answer? And how do you come up with that answer? I am not talking about generic silicon valley answers like "making the world a better place", but actual targeted answers.</i><p>The answer is in your question, in my opinion. <i>Targeted answer</i>. The underlying assumption is that you are asked this during an interview after your "job hunting", which means that you have applied to that company, which should mean that you have read about it, looked at what they're doing, and was interested in joining them.<p>You can reply with the reasons that made you consider that company. Explain how you may help. Ask questions about what they're having trouble with, what they're using, why they made certain decisions, what they have considered, options they may have overlooked, aspects you could help with right away, adjacent or support skills, code you wrote to solve that problem or expertise you have on that topic. This is, after all, what you will be doing once you're hired and you might as well do it during the interview.<p>One more thing: doing this upstream helps tremendously. Finding a way to communicate your value and the reasons you want to join the company <i>before</i> the interview increases your chance to get an interview and puts you in a different queue. It can be a short email. Saying what you liked, why you want to join, which ways you may be useful, which aspects you may need to improve to be useful.