Methodology
How zipradar sources its data
Published 2026-04-20 · Last reviewed 2026-04-24
zipradar federates twelve public datasets behind one page per US address. This page documents where each dataset comes from, how often it refreshes, what licensing applies, and where the limitations are. Every claim on every zip page links back to the primary source named here.
Principles
- Primary sources only. Federal agencies, state primacy agencies, and county recorders. No blog aggregators, no scraped third parties.
- Regulatory refresh cadence honored. If the EPA publishes SDWIS quarterly, zipradar refreshes quarterly. Data that should be fresh daily (air quality) is refreshed daily.
- No personally identifying records cached. Homeowner names, deed signatures, and the federal sex-offender registry are off-limits for caching.
- Graceful degradation. Where coverage is partial (property tax is a top-50-metros v1 rollout), pages say so explicitly and link to the county assessor's portal.
Source list
EPA SDWIS
Drinking water violations
- Refresh
- Quarterly
- License
- Public domain
EPA LCRR / RTI Lead Pipe
Lead service line inventory
- Refresh
- Quarterly as state agencies report
- License
- Public domain / RTI attribution
EPA Map of Radon Zones
County-level radon risk
- Refresh
- 1993 baseline + state overlays
- License
- Public domain
FEMA NFHL
Flood zones by address
- Refresh
- Quarterly LOMA updates
- License
- Public domain + FEMA disclaimer
USDA Forest Service
Community-level wildfire risk
- Refresh
- Annual
- License
- Public domain
EPA AirNow
Real-time and historical AQI
- Refresh
- Hourly real-time, daily historical
- License
- Free API with attribution
FBI UCR
Crime statistics per agency
- Refresh
- Weekly rolling uploads
- License
- Public domain
NSOPW
Sex offender registry
- Refresh
- Deep-link only (real-time)
- License
- Privacy statute — link only
County assessors
Property tax millage and assessments
- Refresh
- Annual reassessment
- License
- Public records (per jurisdiction)
County recorders
Deed transfers (aggregated only)
- Refresh
- Daily filings
- License
- Public records
NCES EDGE / CCD
School district boundaries and stats
- Refresh
- Annual (one-year lag)
- License
- Public domain
Municipal planning departments
Zoning classifications
- Refresh
- Annual plus ad-hoc rezonings
- License
- Public records
Where we are today
zipradar shipped on 2026-04-20. The site scaffolds are live before address-specific data ingestion so that search engines can index the structure and authority pages while the ETL layer fills in zip and county data through Week 2. Every page currently carries the methodology link; per-page source citations appear as each dataset lands.
Limitations
- Property tax and deed coverage begins with the top 50 metros. Smaller counties link directly to the assessor portal until coverage expands.
- Radon is a county-level indicator. Zone 1, 2, or 3 classifications are a regional signal — at-home testing remains the only address-level measurement.
- NSOPW is deep-linked only. Registry contents, names, and photographs are never cached on zipradar.
- FBI UCR has known reporting gaps for some agencies and years. Pages flag missing reports rather than interpolating.
- Municipal zoning schemas vary by city. Where a city publishes structured zoning data, it is aggregated and translated; elsewhere the page points to the local planning department.
Corrections
If something looks wrong, email contact@editnative.com with the URL and the authoritative source that contradicts the claim. Confirmed errors are corrected within 72 hours and noted on the affected page.
About the author
zipradar is built and maintained by Paulo de Vries. Independent, solo-founder, no investors, no data sales. More on the about page.