Apple - Mac OS

SpiderNet - Macintosh Online Service
Apple Support - Older Apple software downloads
Low End Mac Low End Mac - Classic Mac OS Downloads and Updates
The Apple Wiki
MacKiDo explains Mac technoslogy.

OpenCore Legacy Patcher for installing more recent macOS versions on hardware that officially does not support those version. GitHub - dortania/OpenCore-Legacy-Patcher.

Hackintosh.com links to everything you need to build a Hackintosh and get macOS Tahoe (macOS 26) as well as many earlier versions of Mac OS X running on an unsupported computer.

SheepShaver is an open source PowerPC Apple Macintosh emulator. Using SheepShaver (along with the appropriate ROM image) it is possible to emulate a PowerPC Macintosh computer capable of running Mac OS 7.5.2 through 9.0.4. Builds of SheepShaver are available for Mac OS X, Windows and Linux. See also: http://sheepshaver.cebix.net/SheepShaver.

7402.org - Blog - Sandboxing a third-party macOS app to restrict writing to one folder

GitHub - adespoton/utmconfigs Config files for booting Mac OS 7-9, OS X and macOS on UTM emulator.

MacStrategy is a web site with lots of free (technical) information and news about Apple products with a specific slant to Europe.

Macmaps - Upgrade Paths for Macs running Intel & and Apple Silicon CPUs

OSXDaily - How to Find Comprehensive Mac System Info via Terminal:

system_profiler SPSoftwareDataType SPHardwareDataType

GeeksChalk - How to Download MacOS Installers for New & Old Versions

Apple - Support - Documentaation - Mac
Apple Developer - Documentation Archive
Apple Developer - Documentation

University of Utah - Mac Managers
Marriott Library – Apple Infrastructure Blog Apple Support & Integration in a Higher Education Heterogeneous Environment. Has, among other things, links to the MacAdmins Meeting Archived Presentations and Slides that is held every month.

OS X Mavericks (10.9)

Mavericks Forever. Or: How to still keep running on macOS 10.9.
ars technica - OS X 10.9 Mavericks: The Ars Technica Review
MacRumors - OS X Mavericks: Everything We Know

Compatible applications

In most cases these are older versions of the applications in question that may have security issues (CVEs) that were only fixed in later versions. DO NOT use these applications on untrusted input/files!

Name	Description	Link	Remarks
AppCleaner	Thoroughly uninstall apps.	AppCleaner	Offers version 2.3 for Snow Leopard to Mavericks.
Audacity	Audio editor.	Audacity - Download for macOS	Offers a link at the bottom to older versions, but they are hosted on fosshub.com, a site with horrid ad-banners.
Bean	A macOS word processor.	Bean	Offers version 3.2.5 for Mavericks.
CotEditor	Text Editor	CotEditor - Archives	Offers older versions of CotEditor, among which version 2.5.7 for Mavericks.
CrossPack	Commandline tools for Atmel AVR microcontroller development.	CrossPack	Runs on Mac OS X 10.6 and higher.
HandBrake	Media converter.	HandBrake - Old Releases	Use version 1.1.2 (HandBrake - Docs - System requirements).
iTerm2	A Terminal replacement.	iTerm2 - Downloads	Offers older versions of iTerm2.
itsycal	A tiny menu bar calendar.	Mowglii - itsycal - Verion History	Offers version 0.8.15 for macOS 10.8+.
Little Snitch Requires license.	Informs you whenever a program attempts to establish an outgoing Internet connection. You can allow or deny these connections, or define rules to handle future attempts automatically.	Little Snitch - Previous Versions	Offers older versions of Little Snitch, among which version 3.6.4 for Mavericks.
Lyn	Organize, view, edit and share your photos.	Previouw versions of Lyn	Offers older versions of Lyn, among whicht version 1.13 for Mavericks.
MacVim	Mac version of the Vim text editor.	MacVim - r182	Use MacVim_10.9.dmg. r182 will be the last version with a legacy release that supports Mavericks
Onyx Maintenance Deeper	Utilities for system customization.	Titanium Software - Utilities for Mac	Offers current and many older releases of OnyX, Maintenance, and Deeper.
Platypus	Create applications from commandline scripts.	Platypus	Use version 5.3.
Radio Silence Requires license.	Lets you monitor and block apps that try to phone home	Download Radio Silence	Offers versions for OSX 10.6 and higher.
Skim	A PDF reader and note-taker.	SourceForge - Skim - Files	Offers current and older versions of Skim. Use version 1.5.13 (System Requirements).
Sloth	Show all open files and sockets in use by running processes.	Sloth	Use 2.9 on Mavericks. 3.2 is said to work but 3.0 to 3.2 all crash at startup. All versions.
Sublime Text Requires license.	Text editor.	Sublime Text - Download	Version 4 build 4200 starts on Mavericks, but has crashes (after a few minutes of testing). Version 3 also works, and version 3.2.2 build 3211 seems to work better (from a few minutes of testing).
The Unarchiver	For extracting various archive files.	MacPaw - Download older versions of our software	Offers older versions of The Unarchiver tool. Use version 4.3.0 (for 10.7 and later) instead of 4.3.6 (for 10.9 - 10.14) as the latter one crashes/hangs.
VLC	Video and audio player.	VLC for Mac OS X	Offers current and many older releases for Mac OS X.
Witt Software Requires license.	Several applications/utilities for macOS.	Witt Software - Compatibility List	Offers older versions of Network Radar, PDF Squeezer, PDF Protector, Remote Wake Up, and Screenshot Path that support Mavericks.

Support Articles

Apple security updates
Update macOS on Mac
TCP and UDP ports used by Apple software products
Create a bootable installer for macOS
Mac startup key combinations
If your Mac doesn't start up all the way

Mac OS X 10.5 Server - Technical Specifications

OS X Lion Server - Technical Specifications

Documentation - OS X Mavericks has links to the (security) updates for Mavericks.
Download Security Update 2016-004 Mavericks
Download OS X Mavericks 10.9.5 Update (Combo)

OS X El Capitan - Technical Specifications
Download OS X El Capitan 10.11.6 Combo Update

macOS High Sierra - Technical Specifications

Xserve - Technical Specifications for G4 Xserve.
Xserve G5 - Technical Specifications
Xserve (2009) - Technical Specifications

Mac OS 9

Apple Support - Mac OS 9: Available Updates dead link, use archive.org - Apple Support - Mac OS 9: Available Updates.
archive.org - Apple - Mac OS 9.2.2: Document and Software
Apple Support - Multicountry directory - Dutch Mac OS 9 and lower updates dead link, use archive.org - Apple Support - Multicountry directory - Dutch Mac OS 9 and lower updates.

Apple Support - Multicountry directory for software relevant to other languages. Links for 9.2.x updates seem to be dead. Use this as a starting point to get the different language versions. Just remove the http://web.archive.org/web/20100917074207/ from the link to the .smi.bin file. Or try here instead for the updates for the US English version.

Pure Mac - Mac OS 9 Updates
Updates for Mac OS 9
OS 9 Forever.com
Macintosharcive.org's mirror of max1zzz.co.uk contains all 9.x.x updates upto 9.2.2 in several language versions.

Archived - Mac OS 9.2.2: Document and Software
OS 9.2.3 is the unofficial update to Mac OS 9.2.2. It adds 17 system menus with 180 new commands to the Finder. Most of them are disk and file utilities. This is NOT an Apple product. By Cliff Huylebroeck. Dead link, use archive.org - OS 9.2.3.

Mac OS Server

Apple - macOS Server User Guide

Apple Support - About macOS Server 5.7.1 and later

The Apple Wiki - Firmware/Mac Server/10.6.x with download links for 10.6.1 to 10.6.8 for Mac OS 10.6 Server.

Apple - Business Essentials One complete subscription that seamlessly brings together device management, 24/7 support, and cloud storage. With Apple Business Essentials, your small business can easily manage every iPhone, iPad, Mac, and Apple TV — every step of the way.

Apple Community - macOS Server Replacement: Calendar, Contacts, Mail, VPN, DNS
Apple Community - End of macOS Server, Alternative ?

GitHub - enzo-zsh/awesome-macos-server A list of free and paid apps to turn your Mac into a server.

7402.org - Blog - Replacement of macOS Server: Calendar, Contacts, and Mail

archive.org - Apple - Mac OS X Server - Resources - Documentation has the links to PDF files for Mac OS 10.6 Snow Leopard Server.
archive.org - Apple - Mac OS X Server - Resources (2009) has links to the 10.5 Leopoard Server PDFs that are also available from archive.org. Found via MacRumors - Forums - OS X Server on PPC.

Searching DuckDuckGo for the following site:URL terms gives links to many of the Mac OS X Server PDF files, but only for 10.4 Tiger.

site:https://images.apple.com/server/docs
site:https://www.apple.com/server/docs

Shaw's Rhapsody Resource Page

Applications

GitHub - phmullins/awesome-macos. A curated list of awesome software for Apple's macOS.
GitHub - iCHAIT/awesome-macOS A curated list of awesome applications, softwares, tools and shiny things for macOS.
Maverick Mac A curated list of awesome mac applications and utilities.
Mac Treasure showcases apps that are lesser-known and underrated by the community, some rare gems that need to be discovered and shared.
GitHub - ringomdm/mac-admin-tools. Free mac admin tools.
FreeMacApps A carefully curated collection of the best free and open source applications for macOS, featuring hidden gems from GitHub.
Mac App List
Awesome macOS Open Source Applications

GitHub - BITespresso/createinstalliso. Creates a bootable ISO image from a macOS installer application. This image can then be used to install macOS on a physical or virtual machine.
DiskMaker X is an application built with AppleScript that you can use with many versions of OS X/macOS to build a bootable drive from OS X/macOS installer program (the one you download from the App Store).

Classilla is a free, open source browser for Mac OS 9 and where possible Mac OS 8.6 built on WaMCom, a port of Mozilla to classic Macintosh system. Development has ended in 2021: Old Vintage Computing Research - The final official release of Classilla.
TenFourFox “The world's most advanced web browser. Finely tuned for PowerPC”. Development has ended: TenFourFoxDevelopment - The end of TenFourFox and what I've learned from it.

MacVim Vim - the text editor - for macOS.

Marcel Bresink Software-Systeme. Home of:

Tinker Tool
Tinker Tool System
PrefEdit
PropEdit
and others

Cutedge Systems. Home of MailServe.

GrowlyBird Software. Home of the free apps Growly Draw, Growly Notes, Growly Write, Growly Calendar, Growly Photo, and several other productivity applications and games.

Andrew C. Stone with several iOS and macOS applications.

Sindre Sorhus - Quality Crafted Apps

Witt Software with several macOS applications among which PDF Squeezer, PDF Protector, PDF Text Includer, Screenshot Path, and Network Radar.

Jibapps with Displays for monitor (resolution) management, ThrashMe 3 and ThrasMe for app uninstall, and TunesArt display music album covers on your desktop.

Brushed Type with Doppler Music Player, and Doppler Transfer to send files from Mac to iPhone.

GitHub - Stengo/DeskPad A virtual monitor for screen sharing.

Stairways Software home of Keyboard Maestro a macro program for macOS to automate actions.

Sveinbjorn Thordarson - Software home of:

Platypus: create Mac applications ffrom commandline scripts.
Sloth: GUI for the 'lsof' command for list of open files.
FastDMG: mounts .dmg files faster than Finder.
ManDrake: man page editor.
KatSearch: Findf files on HFS+/APFS volumes by scanning file system catalog.
hear: command line interface for built-in speech recognition.
searchfs: search by filename on HFS+ and APFS volumes (commandline)
osxiconutils: work with .icns files and Finder file icons.
icnsoptim: optimize Apple Icon (.icns) files

Wang CHuijang - Quality crafted apps provides several apps, e.g. Vidwall, and Web Serve.

Calendar and Contacts Server the basis of the Calendar and Contacts server in Mac OS X Server. GitHub - apple/ccs-calendarserver (archived), and GitHub - JohnPritchard/ccs-calendarserver a slightly updated fork. See also: stewart a. | aka firewing1 - Installing the Darwin Calendar Server 2.4 on Fedora 13 or Fedora 14.

Software/Package managers

The MacPorts Project is an open-source community initiative to design an easy-to-use system for compiling, installing, and upgrading either command-line, X11 or Aqua based open-source software on the Mac operating system. To that end we provide the command-line driven MacPorts software package under a 3-Clause BSD License, and through it easy access to thousands of ports that greatly simplify the task of compiling and installing open-source software on your Mac.

Homebrew The Missing Package Manager for macOS (or Linux).