Best mortgage calculator for bootstrapped startups

There are roughly 200+ mortgage calculator tools online, but fewer than 15 are designed specifically for self-employed or startup founders with non-traditional income documentation. The common failure of existing calculators is treating all income the same way—they don't account for the 2-year tax return lookback period, variable monthly revenue, equity compensation, or the fact that lenders often average your last 24 months differently than you'd expect. The real gap isn't in calculation accuracy; it's in education and pre-qualification strategy. A vibecoder entering this space should focus on three things: (1) helping founders understand how lenders actually view startup income before they apply, (2) providing transparent scenario modeling that shows impact of different documentation strategies, and (3) integrating with actual lender requirements so the output isn't just a number but a roadmap. The audience is small but high-intent—bootstrapped founders actively seeking mortgages represent maybe 40,000-60,000 annual searches globally, with concentrated demand in tech hubs like San Francisco, Austin, and New York. Most existing tools ignore this persona entirely, treating them as edge cases rather than customers.