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# HSTS preload checker

Check whether a domain is actually in the HSTS preload list browsers ship, reported as preloaded, pending, unknown or rejected.

This checks the list itself, not your header
Nothing leaves this page until you do. The preload list is the dataset compiled into browsers; whether a domain is in it is separate from whether the site sends a Strict-Transport-Security header. Read the header first with the HSTS Checker on this site, then check membership here.

The four states come straight from the Chromium preload list's status API. Preloading is effectively a one-way decision: once a domain ships in browser builds, removal requests take a long time to propagate because every browser only updates the list on its own release cycle. A rejection is not a ban. The most common causes are a missing includeSubDomains, a max-age under 18 weeks, or any subdomain that does not serve HTTPS on every host; fix the cause and submit again at hstspreload.org.
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## More network tools

- [HTTP header parser](/web/headers)
[All network tools](/network)

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Canonical HTML: https://nutter.tools/network/hsts-preload-checker
Markdown version: https://nutter.tools/network/hsts-preload-checker.md
Plain-text version: https://nutter.tools/network/hsts-preload-checker.txt
Agent index: https://nutter.tools/llms.txt