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User profile for user: BCmart
BCmart Author
User level: Level 1
10 points

What is Cookies folder "HSTS.plist"?

I am trying to permanently delete all cookies on Yosemite 10.10.3 and am wondering about the folder "HSTS.plist" under User/Library/Cookies. The folder and contents seem to contain several cookies that reappear after rebooting, despite being deleted.

I have the following questions, if anyone can help:

1. What Is the folder HSTS.plist?

2 Is the folder safe to delete?

3. How can I permanently delete it and ALL cookies?

Note that I have repeatedly tried to delete all cookies by selecting Safari/Preferences/Privacy - Remove All Website Data AND Clear History and Website Data. On my IOS 8 devices I have also selected Settings/Safari/Clear History and Website Data and Cookies/Always Block.


On Adobe Flash Player Settings Manager, I have also deselected Allow Third-Party Content To Store Data On Your Computer, maximized privacy settings for all options, and ensured that there are no Flash Player websites and/cookies showing on my computer.

MacBook Pro, OS X Yosemite (10.10.3)

Posted on Apr 11, 2015 12:38 PM

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User profile for user: fpDoug
fpDoug
User level: Level 1
80 points

Posted on Apr 11, 2015 2:40 PM

On my system, HSTS.plist appears to contain a list of hosts that have requested secure connections under the HTTP Strict Transport Security protocol (see the WIkipedia entry for "HSTS", for example). It does not contain any data related to my browsing. I would guess that (a) it's safe to delete it, but (b) it will just get recreated or redownloaded the next time you use Safari.


In Terminal, you can use the "plutil" command to examine the contents of the file, e.g.

plutil -convert xml1 -o - HSTS.plist

will show a more-or-less readable version.

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User profile for user: fpDoug
fpDoug
User level: Level 1
80 points

Apr 11, 2015 2:40 PM in response to BCmart

On my system, HSTS.plist appears to contain a list of hosts that have requested secure connections under the HTTP Strict Transport Security protocol (see the WIkipedia entry for "HSTS", for example). It does not contain any data related to my browsing. I would guess that (a) it's safe to delete it, but (b) it will just get recreated or redownloaded the next time you use Safari.


In Terminal, you can use the "plutil" command to examine the contents of the file, e.g.

plutil -convert xml1 -o - HSTS.plist

will show a more-or-less readable version.

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User profile for user: BCmart
BCmart Author
User level: Level 1
10 points

Apr 11, 2015 2:54 PM in response to fpDoug

Very helpful, thanks. You're right, it does come back if deleted. I'm am still unclear as to what might be causing hundreds of cookies to reload after being deleted as above. Note that after redoing those procedures and rebooting in safe mode, so far they have not returned. Any insights you might have on permanenty deleting cookies would be appreciated, but I take from your answer fpDoug that the files in the folder in question are not responsible (or cookies, as such). The sites indicated in my HSTS list are mostly from Google, Yahoo and Apple, and dozens of URLs that I didn't visit and can't easily decipher.

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What is Cookies folder "HSTS.plist"?

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