About REI Underwriter

Real Estate Investment Underwriter

REI Underwriter helps you find, underwrite, and analyze real estate investment deals. Search properties via RentCast and Zillow, pull verified lender rates with source links, run full underwriting analyses, import deals from email, and compare properties side-by-side.

Built for individual investors looking for rental properties and small multi-family deals. Every rate source is cited and verifiable — click any source link to check it yourself.

Features

Property Search

Search RentCast and Zillow for properties by address, city, or zip. Manual entry for off-market deals.

Underwriting Engine

Full residential + commercial metrics: cap rate, cash-on-cash, DSCR, IRR, deal score (0-100), green/yellow/red verdicts.

Sensitivity Analysis

See how your deal performs under different scenarios: rent changes, vacancy spikes, rate increases.

Email Deal Import

Connect Gmail to auto-import deals from InvestorLift, LoopNet, and other listing services.

Verified Rate Sources

FRED national rates, scraped credit union rates, and DSCR/hard money averages — all with clickable source links so you can verify.

Property Comparison

Side-by-side comparison of up to 4 properties with best-value highlighting.

Roadmap

Done Property search (RentCast)

Done Underwriting engine

Done Sensitivity analysis

Done Dashboard with FRED + lender rates

Done Verified source links + info tooltips

Done Property comparison

In Progress Zillow integration (HasData + Apify)

In Progress Email deal import

In Progress Comp data (CompCrunch)

Planned Automated deal alerts

Planned Portfolio tracking

Planned Cash flow projections

API Keys Required

RentCast API Key — Free tier: 50 calls/month. Sign up at rentcast.io

HasData Zillow Scraper — Free tier. Sign up at hasdata.com

Apify Zillow Detail Scraper — Free tier. Sign up at apify.com

FRED API Key — Free. Sign up at fred.stlouisfed.org

Gmail OAuth Credentials — For email deal import. Configure in Settings.

All keys can be configured on the Settings page.

Tech Stack

Python / Flask backend SQLite database RentCast API for property data & rent estimates HasData + Apify for Zillow property details FRED API for national mortgage & benchmark rates Lender scrapers for CU rates (NCSECU, PenFed, NavyFed) Gmail API for email sync nginx reverse proxy