Where the data comes from
Every ZIP page is generated from the GeoNames postal code dataset, snapshot September 26, 2026, published under a Creative Commons Attribution license. We normalise the files, keep ZIP codes as five-character text so leading zeros survive, merge place-name aliases and keep every county association supplied. Nothing is invented: when a code is missing from the dataset, its page says so instead of guessing. The full method and its limits are on About our ZIP code data.
How guides are written and reviewed
Guides explain one question each and point to the primary source that settles it: USPS for mailing, the Census Bureau for ZCTAs and tracts, HUD for crosswalks, and the relevant national postal operator for other countries. Before publication each guide is checked against those sources, examples are tested (spreadsheet formulas are run, ZIP examples are looked up in the dataset) and claims that cannot be sourced are removed.
Editorial principles
- Accuracy over completeness. We would rather say “this dataset cannot tell you” than publish a plausible guess.
- State the limits. Every tool explains what it does not do: reference points are not boundaries, straight-line distance is not driving distance, a county association is not a full crosswalk.
- Primary sources first. Official sources are linked from the page that relies on them.
- Independence. No page is paid for, and pages about third-party services are independent guidance without affiliation. See the disclaimer.
- Privacy by design. Searches, location and bulk lookups run in your browser; we do not run analytics or advertising trackers. See the privacy policy.
Corrections
If a place name, county or explanation looks wrong, tell us through the contact form with the ZIP code or page address. Confirmed errors in our own writing are fixed on the page; issues in the source dataset are noted and reported upstream where possible, and the page's update date changes when its content changes.
Who runs the site
ZIPCodeLookup.io was launched in September 2026 and is operated by the operator of ZIPCodeLookup.io [To be provided by the site operator: legal name]. The site does not list individual authors: guides are produced and reviewed under the editorial process above rather than attributed to a named expert, and we do not claim professional postal, legal or insurance credentials.