Consider the option: Choose an appropriate free software license. I would suggest AGPL v3.0 (or later). Assign all code to the company but include an escape

Consider the option: Choose an appropriate free software license. I would suggest AGPL v3.0 (or later). Assign all code to the company but include an escape (consult a lawyer) so that each of you has enforcement rights should the company go away. Explicitly agree that all of that code is, by understanding, considered to have been distributed to each of you as individuals. Such a choice does not obligate your company to share source however it gives any of the three of you the right to share source. It gives each of the three of you freedom to use the code. Some investors, I would think, might have some trouble with this. For example, a founder could quit, fork all of the code, and start something else. For reasons like that I think the suggestion might inflame some. I suggest that if you presumably all trust one another enough to get to a point where that threat is no longer particularly significant. And that threat ought also to be weighed against the degree of difficulty of someone else doing a clean-room substitute for the code, anyway.