Quick point, he's looking for a co-founder rather than an employee - which means that if (Gabor really means it) you'll have both the freedom and burden of choo

Quick point, he's looking for a co-founder rather than an employee - which means that if (Gabor really means it) you'll have both the freedom and burden of choosing the right tool for the job. Freedom as in you'll be able to make your case for it; burden as in the right tool for the job may not be tool you've liked using or have the experience using (in this case joining, as an employee, a company that uses the stack you'd like to work with may be a better idea). Example: a big enterprise co may force you to use Java to parse text files (because they're by decision a Java shop) even if Java isn't the framework you like for this test. On the other hand, as a co-founder doing a mobile app you may have no choice but to use Java. If you're very determined to only work with certain tools or avoid certain tools altogether (or would like more experience with specific tools) you'd be better being an employee at a company which makes use of these tools (or doing a project of your own with those tools). Of course I've also seen posts that say "I am looking for a co-founder with Python/Rails/MySQL/Oracle/etc... experience" - which seem to be more of "I want the first employee". Founders should be the ones making the decision which stack to use (and using a heuristic other than familiarity or personal like/dislike) - not following a decision that's already been made.