I’ve posted a few old links in my time (as I near 4,000 posts it would be hard not to have some that are broken). But Apple App Store downloads seem to do better with not breaking links. So here are some to old versions of macOS and OS X, in case like me, you always seem to need some old thing for testing:
· 10.14, Mojave https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12
· 10.13, High Sierra: https://itunes.apple.com/us/app/macos-high-sierra/id1246284741?mt=12
· 10.12, Sierra: https://itunes.apple.com/us/app/macos-sierra/id1127487414?mt=12
· 10.11, El Capitan: https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12
· 10.10, Yosemite: https://itunes.apple.com/us/app/id675248567?mt=12
· 10.9, Mavericks: Beta builds available at https://developer.apple.com/download/more/
· 10.8, Mountain Lion: https://www.apple.com/shop/product/D6377Z/A/os-x-mountain-lion
· 10.7, Lion: https://www.apple.com/shop/product/D6106Z/A/os-x-lion
· 10.6, Snow Leopard: https://www.apple.com/shop/product/MC573Z/A/mac-os-x-106-snow-leopard
· 10.5, Leopard: Beta builds available at https://developer.apple.com/download/more/
· 10.4, Tiger: No longer available
· 10.3, Panther: No longer available
· 10.2, Jaguar: No longer available
· 10.1, Puma: No longer available
· 0.0, Cheetah: No longer available
Old versions of server are actually easier. You can download OS X Lion Server: https://itunes.apple.com/us/app/os-x-lion-server/id444376097?mt=12 or macOS Server: https://itunes.apple.com/us/app/macos-server/id883878097?mt=12 and most versions are available on the developer portal at https://developer.apple.com/download/more/.