[batmaniam]

As others have said, it's a bad deal overall. There's many possibilities for the founders to screw you over: from vague milestone definitions, equity being worthless (most startups fail), adding to mental stress, etc.

If you really want to work in the startup, ask if you can own the codebase. That is, you write and own the code, you deploy it on a server you control with a budget they give you. Don't give them a single line of code. If it all blows up, then at least you come out with something you can demo to future companies. If they launch your codebase to production, then you have leverage to ask for a payout from a milestone completed.

If they don't want you to own the codebase, then they're most likely gonna screw you over. Business is business, always remember that.