My question is about Firefox and Chrome.

Is there a possibility to see which sites have set the HSTS flag in my browser?

  • For those on MacOS, the Firefox profile directories are under: ~/Library/Application\ Support/Firefox/Profiles – Ajoy Bhatia Nov 8 '16 at 22:46


  • Open Chrome
  • Type chrome://net-internals/#hsts in the address bar of chrome
  • Query domain: if it appears as a result, it is HSTS-enabled


  • Open file explorer
  • Copy and paste the following path into the address bar of your file explorer
    • On Windows: %APPDATA%\Mozilla\Firefox\Profiles\
    • On Linux: ~/.mozilla/firefox
    • On Mac: ~/Library/Application Support/Firefox/Profiles
  • Double click the folder you see (if you have multiple Firefox profiles, there will be multiple folders)
  • Open SiteSecurityServiceState.txt. This textfile contains sites that have enabled HSTS.
  • 1
    So, there is no list for Chrome, just the queries? – HorstKevin Jul 2 '15 at 18:28
  • 1
    Not as far as I know. You could take a look at the preloaded list: chromium.org/hsts – Michael Jul 2 '15 at 18:51
  • Yes, I know. But there are also sites which I visited which are not on the preload list. – HorstKevin Jul 3 '15 at 7:05

There is a Firefox plug-in called PinPatrol that lists all sites (preloaded and visited) known to have HSTS support.

  • 2
    It is unsupported by current version of Firefox (57+ aka Firefox Quantum) – TimSparrow Dec 7 '17 at 11:31

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