If they’ve got no product or revenue, then it should be an equal split with equal dilution.

Ideas are a dime a dozen. The real work is getting a product to market

You aren’t mentioning what else the startup has or will be contributed by the founders.

If it’s only you putting the work and there’s no other contribution, and you get 10% equity, someone is stealing 90% equity from you, you would just work on your own and have 100% equity.

So focus on what the other founder already has or what they are willing to put, is it money? an idea? exactly how much money? How advanced is the idea, do they have any documents? specifications? market research?

Quantify both sides of the offer then compare them, if your work for 6 months is worth 1/9 of a half assed idea written on a napkin and maybe 100$ of investment but without any actual commital, then you probably need to reevaluate your self worth.

Maybe it’s actually a very advanced idea with loads of documents and research and specifications and previous work done, and maybe he has a fund upwards of ten thousand dollars. Get all of those facts precisely, then and only then will you be able to calculate and commit to equity and time contracts.

As it stands, as someone said, 10% is nothing of nothing.

If someone just point blank offered you 10% of equity in exchange for nothing, then I wouldn’t even consider doing business with that person, no renegotiating, just flat out refusal.

I did this early in my career and it’s pointless. Execution is everything. You don’t need equity in a bunch of dead projects.

I took all cash for a project as the first tech hire. In hindsight, the cash I received was worth far less than a tenth of one percent had I taken equity. Not all projects suck. Telling the difference, very difficult.