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Welcome to!

This is an API that allows applications to easily check to see if a site is included on the Chrome, Firefox, and Tor HSTS Preload lists. To add your site to HSTS Preload lists, you can do so via the Chrome HSTS Preload site; most other browsers base their HSTS Preload list on the list maintained by Chrome.

The API is designed to be as easy to use as possible:



About the data...

The HSTS preload lists are currently being pulled once a day (at night), from the following source files:

Terms of Use

In short: be nice, don't abuse the service, but otherwise feel free to use it. There is no change (and never will be), there are no API keys, and no quotas. This is a free service to help the community.

About this project...

This is provided and maintained by Adam Caudill; if you have any questions, please feel free to contact me.

Source code for this site is available on Github.

Hosting provided by: