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NSOPW — why zipradar deep-links instead of caching the registry
Of zipradar's 12 datasets, only one is deep-link-only: the National Sex Offender Public Website (NSOPW). The other 11 we cache, transform, and present alongside cited sources. NSOPW is different — and on purpose.
Published 2026-04-25 · Last reviewed 2026-05-13 · methodology
What NSOPW is
Operated by the US Department of Justice, NSOPW is a federated search across all 50 states + DC + 5 territories + tribal registries. There is no single combined dataset; each jurisdiction publishes its own under its own statutes.
Search runs against state RSS feeds + state APIs in real time. Results are returned as state-jurisdiction records, not federal records.
Why caching is forbidden
State statutes typically require results to be served fresh — caching delivers stale data that can wrongly include a person who has been removed from the registry, or wrongly exclude someone newly added.
NSOPW's federal Terms of Service prohibits scraping, caching, or reproducing the registry data. Operators caught violating face civil liability under the Adam Walsh Act.
Some state statutes also criminalize unauthorized republication. Texas Code § 62.005 is one example.
How zipradar handles it
Per ZIP page: a deep-link constructed with the ZIP code as a search parameter. We do not pre-fetch results; we send the user directly to NSOPW where they get the official, real-time, jurisdiction-correct view.
We never store names, addresses, photos, or any other registry data. We never count results. We never log the destination.
Our llms.txt explicitly flags NSOPW as do-not-cache for AI crawlers. Our robots.txt allows NSOPW deep-link discovery but our /api/manifest.json marks it as a non-cache endpoint.
Why this matters for trust
Real-estate decisions made on stale registry data hurt people on both sides — buyers who think a neighborhood is safer than it is, and individuals who have completed their sentences but whose old records persist incorrectly.
Deep-linking respects the legal architecture: the state knows its own jurisdiction, and the user gets the official answer with the right disclaimers.
Related zipradar topics
Glossary terms used here
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