Mashvisor is built for discovery: neighborhood heatmaps, Airbnb data, and rental projections that show what a market could earn. A projection is not protection — it will not tell you the price at which a specific deal stops working, and it has no verdict to give. ReInvestIQ underwrites the address itself: rent validated across three sources, a computed maximum offer, and a GO / NO-GO verdict you can stress-test with rents down and rates up. Here is the side by side. Per-deal underwriting with a loss floor: multi-source rent validation, a computed maximum offer with exact repricing levers, and a verdict that survives — or honestly fails — a downside scenario.