DealCheck is a fast, well-built calculator: type in price, rent, and expenses and it returns cap rate, cash-on-cash, and a cash-flow projection. What a calculator cannot do is push back. If the rent you typed is $300 optimistic, DealCheck computes a beautiful return on a bad deal — it has no way to know. ReInvestIQ validates every input against primary-source data, computes the maximum you should offer, and returns a GO / NO-GO verdict you can stress-test with rents down and rates up. Here is the side by side. Underwriting that pushes back: inputs validated against primary-source data, a computed maximum offer with exact repricing levers, and a verdict that names the threshold a failing deal missed.