One-click rental-property underwriting: compile assessor + comps fast

Executive Summary

Small-scale real-estate investors, wholesalers, and private lenders spend hours assembling assessor records and comparable-sales data to underwrite deals; with roughly 3.0 million active investors in the U.S., that manual work scales into meaningful time cost per deal (commonly 1–4 hours) and leads to inconsistent outcomes across counties. Public records are heterogeneous, property identifiers are inconsistent, and MLS access is fragmented, which makes basic underwriting—assessing tax history, lot details, and nearby comps—slow, error-prone, and expensive for users who cannot justify full-service broker reports. You could build a one-click underwriting platform that pulls assessor databases, tax records, MLS/comps, and rent estimates via APIs and LLM-powered extraction, then normalizes fields, selects best-fit comparables, and produces a stamped PDF report plus machine-readable output in under five minutes per property. Delivered as a web app with an API and tiered billing (subscription for active users plus per-report add-ons), the product targets the 3.0M investor base and aligns with an addressable market of about $1.2B (roughly $400 ARPU/year). Market conditions favor this approach: greater API availability, improved LLM extraction for messy public records, and the ongoing DIY investing trend make fast, low-cost underwriting commercially attractive—reflected in a Market Score of 92/100 and Revenue Potential of 88/100. To win, prioritize provenance, explainability, and local accuracy by attaching confidence scores, surfacing source links, and recruiting county-level validators, because medium competition will compete on speed and price but often lack traceable accuracy. The real challenges are data licensing and MLS access, the need for continuous model retraining to handle jurisdictional edge cases, and building initial trust with paying users; if you budget for early investment in ground-truthing and compliance, this is a viable product to pursue.