How to block and delete cookies in High Sierra

It’s pretty common practice for websites to store cookies on your computer, and despite their bad reputation some cookies can actually improve your browsing experience.

Cookies are how websites identify repeat visitors, allowing them to deliver a version of their website that’s optimised for each visitor. For example, if you tell a website to display its prices in pounds sterling on your first visit, then this the currency you’ll see on every subsequent visit.

Websites can also use the information stored in cookies to auto-fill forms, so after you’ve entered your username, email address or postal address into a website once, you may never need to enter this information again. And, if you enjoy a spot of online shopping then cookies are how websites remember the contents of your shopping basket, even if you navigate away from that site and then return to complete your purchase at a later date (although this may be a good or a bad thing, depending on how much you love online shopping!)

Despite the benefits, many people are uncomfortable with the thought of being recognised, and are happy to sacrifice the convenience of cookies in return for some added privacy. It’s also worth noting that not all cookies are good cookies! Some third party advertisers may place cookies on your Mac, and then use them to track your browsing activities across the World Wide Web, which is a disconcerting thought!

It’s always been possible to modify how your Mac manages cookies, but High Sierra makes a few changes to these settings. If you’ve recently upgraded to High Sierra, then in this article I’ll be exploring these updated settings, including how you can prevent any cookies from being placed on your Mac.

Remove cookies for specific websites

Safari lets you review a list of all the websites that have stored cookies and tracking data on your Mac. From here, you can delete the data associated with a specific website, or even remove all cookies and tracking data from your Mac with the click of a button.

This is particularly useful for identifying third party advertisers who may be secretly gathering information about you, or if there are certain websites where you’d simply prefer to remain anonymous! Just be aware that removing the data associated with a website may result in you being logged out of that website.

To see exactly which websites have placed data on your Mac:

  • Launch the Safari web browser.
  • Select ‘Safari > Preferences…’ from the toolbar.
  • Select the ‘Privacy’ tab.
  • Select the ‘Manage Website Data…’ button.
  • The subsequent menu lists all the websites that have stored data on your Mac. To remove the data associated with a particular website, select that website and then click the ‘Remove’ button.

  • Alternatively, if you want delete all the tracking data and cookies that have been placed on your Mac, then click ‘Remove All.’
  • Once you’ve finished, click ‘Done.’

Blocking Cookies

Some cookies may be beneficial, but if you’d prefer to remain as anonymous as possible, then you can prevent any cookies from being placed on your Mac. Note that blocking cookies may prevent some websites from working correctly, so if you encounter any issues after opting to block cookies, then you may have no choice but to re-enable them.

To block cookies:

  • Select ‘Safari > Preferences…’ from the Safari toolbar.
  • Make sure the ‘Privacy’ tab is selected.
  • Select the ‘Block all cookies’ checkbox.

This setting may prevent future cookies from being placed on your Mac, but it won’t remove the ones that are already present on the system. After completing this step, it’s recommended that you click the ‘Manage website data…’ button and then remove all the cookies and data that have already found their way onto your Mac.

Additional security options

If you’re concerned about websites and third parties tracking your online activities, then Safari has a few more settings you may want to enable, in addition to blocking and removing cookies.

Prevent cross-site tracking

Some third party advertisers can place cookies and other data on your Mac, even if you’ve never actually visited their website.

Since you probably don’t want some mysterious third party gathering information about you, by default Safari only accepts cookies from websites that you explicitly visit, but it also offers a ‘Prevent cross-site tracking’ option that can make it even more difficult for third parties to track you. Once this option is enabled, third party tracking data is periodically deleted.

  • Navigate to ‘Safari > Preferences…’
  • Select the ‘Privacy’ tab.
  • Select the ‘Prevent cross-site tracking’ checkbox.

Send a ‘Do Not Track’ request

When you enable Safari’s ‘Ask websites not to track me’ checkbox, Safari will send a ‘Do Not Track’ request to all the websites you visit, and will also send this message to any third parties who may be tracking you.

Frustratingly, websites are under no obligation to honour this ‘Do Not Track’ request, so it’s debatable how much of an impact this actually has, but if you’re concerned about your online privacy then it’s still worth enabling this option:

  • Navigate to ‘Safari > Preferences… > Privacy.’
  • Select the ‘Ask websites not to track me’ checkbox.

Before you go

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About the author


I've been a passionate evangelist for Apple and the Macintosh throughout my working life, my first love was a Quadra 605 working with a small creative agency in the south of Norfolk UK in the mid 1990's, I later progressed to other roles in other Macintosh dominated industries, first as a Senior graphic designer at a small printing company and then a production manager at Guardian Media Group. As the publishing and printing sector wained I moved into Internet Marketing and in 2006 co-founded blurtit.com which grew to become one the top 200 visited sites in the US (according to Quantcast), at its peak receiving over 15 million visits per month. For the last ten years I have worked as an Affiliate and Consultant to many different business and start ups, my key skill set being online marketing, on page monetisation, landing page optimisation and traffic generation, if you would like to hire me or discuss your current project please reach out to me here.

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