Are older macOS pre-Big Sur safe? Best web browsers?

Is it Safe to run older versions of Mac OS pre Big Sur ?

What are the best web browsers to use ?


I would to still use these computers because they have all my apps and files

and other than no longer receiving updates they still work good

only the web browsers dont get updates ?

Earlier Mac models

Posted on Jul 18, 2026 9:26 AM

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5 replies

Jul 18, 2026 11:08 AM in response to alex7375

If any of these "pre-Big Sur" computers run Catalina, you could install Firefox. The latest version of Firefox still runs on Catalina.


If they are running Sierra, High Sierra, or Mojave, you could install Firefox 115 ESR. This is an older version of Firefox that was scheduled to stop getting security updates from Mozilla long, long ago. But Mozilla has been giving it lots of "stays of execution" and is now saying they will provide security updates for it until March 2027.


Mozilla Support – Firefox users on macOS 10.12, 10.13 and 10.14 moving to Extended Support Release


If they are running something earlier than Sierra, you are probably out of luck. For example, I don't know if you can still download Firefox 78 ESR (which runs on El Capitan, among others), but even if you could, it is ancient, and has not gotten even "critical security updates" for several years.

Jul 19, 2026 12:31 PM in response to alex7375

Macs even older than those eligible to run Big Sur continue to receive periodic XProtect updates. The latest was issued three days ago, on a fifteen year old Mac.


Effective defenses against malware and other threats - Apple Community remains applicable to all Macs regardless of age.


As Servant of Cats noted the latest commonly available browser that remains updated and useful is Firefox.

Jul 18, 2026 12:11 PM in response to alex7375

alex7375 wrote:
Is it Safe to run older versions of Mac OS pre Big Sur ?

Yes, it is safe ... (High Sierra & later) as long as you practice safe behavior on all online activities. If you don't know what that means, a new Mac isn't going to make any difference.


Others have answered your question about browsers. In my own case, I use Firefox with the addition of Privacy Badger & uBlock Origin browser plugins.

Jul 19, 2026 1:30 PM in response to alex7375

as other have already stated, Firefox is still supported for many of the older macOS.


as far as using older macOS, I have Catalina installed on an external drive so I can still use some antiquated hardware that will not run on any macOS after that. if it was unsafe, I would not continue using Catalina.


just refer to the article John Galt has linked to you to practice safe computing habits.

Are older macOS pre-Big Sur safe? Best web browsers?

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