What equity should a marketing co-founder get?
Short answer
If you join before there is revenue and you are doing the work rather than advising on it, meaningful co-founder equity is normal — often in the 20 to 50 percent range depending on when you joined and what the developer had already built. If you join a product with traction, you are closer to an early employee or a freelancer with upside, and the number drops accordingly. Whatever you agree, vest it over time and write it down before you start.
The longer version
The number depends almost entirely on when you join and what already exists. Joining a pre-revenue product where the developer has built a prototype and nothing else is genuinely co-founding, and co-founder equity — often somewhere in the twenty to fifty percent range — is normal. Joining a product with paying users and growth is a different transaction; you are early staff with upside, and the number is usually single digits.
What matters as much as the percentage is the structure. Vest it, over three or four years, with a cliff. This protects both of you: it protects the developer from handing a third of the company to someone who leaves in month two, and it protects you from being edged out after you have done the work. A founder who resists vesting is telling you something.
Write it down before you start. Not a term sheet with lawyers necessarily, but a document that says what each of you is committing, what the split is, what happens if someone leaves, and who decides what. The conversations that kill founding pairs are almost never about the number. They are about the two people having remembered the conversation differently.
The full argument, with the rest of the picture around it:
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