I was offered a position of software engineer at a company of 3 people, but it's technically just one (more on that later). I was offered just about market value for an entry software engineer in my area and about 1% of ISO over a 4 year vesting period.
Here's the catch: The majority of the salary is deferred until they secure the entire seed round of investing they were looking for (currently they have 1/3rd). Two of the co-founders are no longer there (full-time job and school) but are said to continue "helping out when possible". I'd basically be one of two people working on the product full-time.
Is it fair to ask for a little more equity? I had something in the range of 3-5% in mind before they gave me an offer. Is there a better form of equity to ask for other than ISO? If I leave the company in 2 years, do I keep the stock I own but forfeit the 2 additional years that haven't vested?
First, make sure you read this: Forming a new software startup, how do I allocate ownership fairly? Lots of good stuff in there (and in the comments too).
There's a big question about time and effort. How much has gone into it already? If not that much, then you should get a bigger share.
Is the product live? If it's still in development, pre-launch, then you should get more (perhaps even be considered a founder). It all depends on those pesky little details which only you (and they) know.
If they want to defer a big chunk of your salary, then you have to ask what guarantee you'll have of getting it. For example, if they fail to get all their funding, will you get paid? I'm guessing not. So, in that case you have a massive gamble on their efforts. They also gamble on yours (they need you to build something to get the money). At this point, you're looking more and more like a founder. You certainly should get more options if you have no guarantee of getting paid your deferred salary.
As far as the vesting, yes, that's how it works. If you vest over four years (sounds reasonable to me) and you leave after two, then you get what is vested and you lose what is not. Remember, you're getting options, not stock. You're getting the right to purchase at some price, not actual shares in the company. So, you'll keep those options not that stock. The options will expire at some point if you don't exercise them (maybe 10 years or so - check the terms).
Let me add these points:
The two co-founders who aren't working for the company full-time: are their Founder's Shares subject to vesting? If not, then there is a high risk they won't contribute equally to the company's future growth. If so, then if they don't wind up working for the company, their shares should accrue back to the company and accrete to all other stock-holders equally.
It would be a major red-flag for me if the Founder's Equity weren't subject to vesting. I'd insist that it be. This is a critical question that needs answering.
With regard to your deferred compensation, I would ask either -
If you believe in the product and the market and, most importantly, your ability to deliver the product, then it might be a great opportunity, especially if you can resolve these issues.