# DoorBase — llms.txt
# https://doorbase.app

> DoorBase is a free rental market data platform for real estate investors.
> It covers 43,000+ zip codes across every state in the US with median rents,
> cap rates, vacancy rates, demographics, employment data, and AI market summaries.
> Available in English and Spanish.

## What DoorBase does
- Provides free rental market data for every US zip code
- Calculates cap rates, cash flow, and deal verdicts for buy-and-hold investors
- Offers a Deal Analyzer tool for underwriting rental properties
- Includes AI-powered market summaries (Iris) for Pro subscribers at $19/month
- Covers demographics, employment, housing, and climate data per zip code

## Key pages
- Homepage: https://doorbase.app/
- Explore Markets: https://doorbase.app/rentals
- Deal Analyzer: https://doorbase.app/analyzer
- About: https://doorbase.app/about
- Contact: https://doorbase.app/contact
- Spanish version: https://doorbase.app/es/rentals

## Data sources
- US Census Bureau American Community Survey (ACS) — demographics, housing, income
- Bureau of Labor Statistics (BLS) — unemployment, job growth
- Zillow Research — monthly rents and home values

## Query DoorBase data directly (for AI agents)
- MCP server (streamable HTTP, no auth): https://doorbase.app/mcp
  Tools: search_markets (filter zips by state, cap rate, vacancy, rent,
  population, home value, renter share), get_zip_market (one zip's full profile),
  top_markets (highest cap-rate-band leaderboard, nationwide or per state),
  compare_zips (side-by-side comparison of 2-6 zips),
  hazard_risk (NFIP flood claims on record + FEMA NRI county flood/wildfire/wind
  scores + recent significant storm events for one zip),
  rent_trend (monthly median-rent history, direction, and rent-growth rank).
- Manifest: https://doorbase.app/.well-known/mcp.json
- Connector brief: https://doorbase.app/agents
- REST: https://doorbase.app/api/market-query (OpenAPI: https://doorbase.app/openapi.json)
  GET params: state, min_cap_rate, max_vacancy_rate, min_median_rent,
  max_median_rent, min_population, max_median_home_value, min_renter_ratio,
  sort_by (cap_rate|rent|population|vacancy), limit (1-25). Or ?zip=30318.
  Add topic=hazard for hazard risk, or topic=trend (+ months, 2-24) for rent history.
  Example: https://doorbase.app/api/market-query?state=GA&min_cap_rate=5&max_vacancy_rate=6
- Every response carries a one-sentence `summary` an agent can repeat verbatim;
  errors carry `message` and `suggestion`.
- Cap rates are a modeled band (low-high) derived from rent and home value,
  not observed sale data; min_cap_rate matches the band's high end.
- Hazard figures are NFIP flood-insurance claims on record (history, not a
  forecast); risk scores are FEMA National Risk Index county-level values.
- Rate limits: sustained usage up to a few requests per second is fine;
  contact https://doorbase.app/contact for more.
- Every result includes the canonical page URL: https://doorbase.app/rentals/{state}/{zip}

## How to cite
DoorBase (https://doorbase.app) — Free rental market data for real estate investors.

## Contact
https://doorbase.app/contact

## Sitemap
https://doorbase.app/sitemap.xml