[ilikepi]

From the README:

> [...list of macOS installer apps...]

> Mac users can download theses files from the App Store.

This isn't really accurate. It's not possible to find and download macOS releases older than the current release. The only exception I was able to find a few months ago is if you've already downloaded them once previously while signed into the App Store on a different machine. I believe in that case an old release can be downloaded on a new machine from the Purchased list after signing in under the same account.

EDIT: formatting; clarification

[initself]

I just downloaded El Capitan today from the App Store from the same machine I installed from.

[djrogers]

Yes, releases older than Sierra can still be found if you had previously downloaded them, but Sierra is gone and presumably High Sierra will be as well once it’s been replaced.

[miles]

How to download macOS Sierra

https://support.apple.com/en-us/HT208202

https://itunes.apple.com/us/app/macos-sierra/id1127487414?ls...

[beefhash]

It's also not possible to download newer macOS releases than the ones deemed compatible with your Mac by the Store.

[bluedino]

Plus, old versions expire after a certain time due to Apples signing of the files

[mikeash]

You’re thinking of iOS. That doesn’t apply to the Mac.

[chrisper]

Yes it does. I had a USB Image of the OS X Installer I created some years ago. Was not able to install it (since the certificate expired). I had to reset the Systemclock to something like 2015.

But I guess they don't expire like iOS updates do.

[feelix]

That was due to a separate bug related to code signing. The poster above you who got downvoted was correct.

[chrisper]

How is it a bug that a certificate expires? Every certificate expires at one point and if you try to use in the future it will not work as it is expired. That is not a bug. It is a feature.

[mikeash]

iOS requires permission from Apple, so resetting the clock doesn’t work.

[bluedino]

https://www.macrumors.com/2016/03/03/older-os-x-installers-b...