If they don't pay for your living expenses I would classify you as a co-founder, not as an employee. The share you get should correspond to how much you contrib

If they don't pay for your living expenses I would classify you as a co-founder, not as an employee. The share you get should correspond to how much you contribute and how much they have done already. Anything from 15%-35% can be reasonable, but it very much depends. The real questions are: a) can you afford to take this risk? Can you take the risk financially and qua opportunity cost? b) do you think all three other founders have valuable skills? c) are the other founders smart and willing to work hard? d) do you think they have common sense? e) do you get a say in the way the company is run, or are you expected to shut up and code? f) do you trust the other founders not screw you over? Are you absolutely sure they're trustworthy? g) do the founders get along great with each other and with you? Are they mentally stable? If you can't answer these questions with a confident YES! you should probably pass on the opportunity. If you have no doubt that other founders are going to accomplish great things, and if you're willing to take a risk, don't worry about having 5% less equity than you'd like to have. A 15% share in a great company is a lot better than a 35% share in a flaming train wreck. Oh, and get things in writing, just in case.