I operate a small-medium fleet of macOS and OS X computers. For various legacy software and licensing reasons, the fleet operates on each release from 10.9 (Mavericks) to 10.15 (Catalina, current). All of these releases are free to download via the App Store and from Apple directly via their website.

I am not a member of any Apple program that provides access to early and/or special macOS / OS X builds. I am reliant on common sense and trial-and-error to maintain a set of OS installers from official sources. Sometimes the App Store installers are silently updated, especially when minor updates are applied outside of a combo updates release.

Right now, I check every couple of weeks and spend time downloading ~5-8GB, check the build number and invariably see it hasn't changed, then ditch the download. This seems wasteful.

I would like to be able to check a location online that can tell me the current build number of the active release, for example the one that's downloadable from the App Store.

Is there a location I can check that will tell me the build number of the freely-available macOS & OS X releases?

Thank you.

Edit #1: addressing @Jay-Way's post below with a screenshot. It looks like Mactracker doesn't have 10.15 (Catalina) details at all, so I'm guessing it's a manually-maintained list by the author or a third party.

Mactracker macOS panel

  • 2
    It's not necessarily the build number which changes between the latest releases but also other details. AFAIK a lot of older macOS installers (Sierra, High Sierra, Mojave) have been replaced with a newer installer with the same payload (= build number). The only difference is the new certificate/intermediate cert authority. The old ones became invalid in the meantime...
    – klanomath
    Oct 31, 2019 at 14:06
  • Hi @klanomath - it's worse than that at the moment, the new installers are almost impossible to differentiate - see the top of apple.stackexchange.com/a/309400/85275 for a first-look at them.
    – Tetsujin
    Oct 31, 2019 at 14:15
  • Thanks @klanomath - I did not know that. Would checking for the 'last modified' date (or equivalent) be more appropriate than the build number? Oct 31, 2019 at 14:16
  • In my opinion the older installers (10.9-10.12) won't be published with a new build number in the future. The newer installers which still receive security updates (10.13-10.14) might get an updated installer (with a new build number) if some really severe security breach/bug is detected. AFAIK the replacement of the invalid certs in pre-Mojave installers is completed. You will probably see new build numbers with 10.15 installers only.
    – klanomath
    Oct 31, 2019 at 15:59

1 Answer 1


There is an app for that :) https://apps.apple.com/app/mactracker/id430255202?mt=12

It seems like there is no web service or similar providing this info, but I just took a quick look at the app and it seems to provide infos on every mac- and iOS, with build informations for every version.

Screenshot: ![mactracker screenshot

  • Thank you @Jay-Way - that looks interesting, I'll give it a spin. My first concern would be whether the author maintains a list if build number and/or dates manually, and the maintainability of them…or whether they wire it into an Apple web service. I will investigate, thanks again. Oct 31, 2019 at 14:21
  • It looks like Mactracker doesn't have 10.15 (Catalina) details at all, so I'm guessing it's a manually-maintained list by the author or a third party. Oct 31, 2019 at 14:40
  • @PeteCooper Yes you're right, there are no entries for Catalina... I've found a small list on wikipedia en.wikipedia.org/wiki/MacOS_Catalina#Releases - maybe that is the point where we should start a crowd maintained website where people can find these type of informations?
    – Jay-Way
    Oct 31, 2019 at 14:49

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