1. Release Notes 1.1.2 - 2018-10-07. Migrated to Swift 4.2; Force Static linking of standard library, which should fix issues running on Mojave.
2. SwiftDefaultApps - Set the default application used for various URL schemes, file extensions, file types, MIME types, and Uniform Type Identifiers. TinkerTool - Gives you access to additional preference settings Apple has built into macOS. Detexify - Draw a symbol and get LaTeX code for it. Dozer - Hide status bar icons on macOS.

I have VLC installed which by default catches sftp:// URL's, so I fixed that using 'SwiftDefaultApps' even though the workflow is using the -a flag. That didn't help. Anyone had this issue? Google isn't much help. Most people just say that one should use ftps, but that's a completely different protocol! Hence, not helpful.

Help, Books, Applications

Apple.com

iCloud.com
Apple System Status
appleid.apple.com - Create an Apple ID.
icloud.com/find/ - Find your device.
Apple Support - Knowledge Base.
Check coverage - Find hardware details, AppleCare etc from a serial no.
Apple Developer Docs - macOS Documentation.
Apple Combo Updates - Several macOS point releases in one download.
Apple Support Downloads - Patches, Security updates, new and old versions of Apple software.
Apple Open Source - Tools and languages (Swift).
Apple Font Tool Suite - command line tools for working with font files.
Apple developer fonts - Apple fonts have a very restrictive licence (only use with Apple software) other more open fonts are available.
macOS Command Line Tools - GCC and make Developer downloads.
Mac OS Compatibility Guide - Which Macs are compatible with a later version of macOS
Tips and Tricks for Mac Management (2009, White Paper PDF).
Apple Support Manuals
Business and Education Support
iPhone Activation Lock

bash versions for macOS

MacOS comes with bash version 3.2.57 from 2007 which is the last version released under GPL2 (Apple don't want to support GPLv3)

Apple do patch serious vulnerabilities in the version of bash they ship, but if you want something more up-to-date, you can keep the default bash install and add a second bash install from GNU or from a package manager like Macports or Homebrew. You can then change the Terminal.app profile to start this new bash shell.

Macports:
sudo port install bash

Homebrew:
brew install bash

To display the installed/current version:
echo $BASH_VERSION
bash --version

Hardware

MacRumors Buyer's Guide - product cycle summary for each Apple computer with buy recommendations.
MacOS Compatibility Guide - Hardware and MacOS compatibility. Apple supply security updates for the current OS + two previous releases.
Apple Support Communities
AppleID - AppleCare login.
AirPrint devices.
AppleCare registration (also buy AppleCare at eBay)
Louis Rossmann - Right to Repair.
Unshaky.app - Supress Double Key Presses - for the faulty Macbook / Pro butterfly keyboards (2016+)

News

AppleInsider
CultofMac
Daringfireball
9to5mac
Ken Segall - Marketing blog.
The Safe Mac - Malwarebytes advice.
SixColors - Apple and other tech news and culture.
Apple.Slashdot
MacOSXhints - 2014 Archive of old Hints & Tips, Q&A
MacRumors
Status: Apple Services, Stores, and iCloud, Dev Centre

Help & Documentation

Apple.StackExchange.com
/usr/share/doc/bash/bash.pdf - OSX Bash built in Help manual.
ifixit.com - Repair guides for Mac.
Google Shell Style guide - some short, sensible advice on coding style.
macOS Boot Disk Structure - EclecticLight.co
macOS Security and Privacy Guide - Github.
manpagez - Man Pages from Huntsville Mac Users Group.
Old Apple Manuals - PDF copies of old (pre 2003) Apple hardware manuals.
Mac Scripter - Applescript Tutorials & forum.
Using Apple Diagnostics (KB HT5781).
Migration Assistant - transfer files from another Mac.
Colour Picker - How to use the Mac colour picker.
Dictionary - How to add Webster's 1913 dictionary to macOS.

macOS Books

[ Full disclosure: I get a finder's fee on stuff you buy from Amazon.com by clicking through this website.
That doesn't cost you anything, but the commissions help to keep the site running ]

OSX: The Missing Manual, Mountain Lion Edition
by David Pogue
The 'must have' guide for all macOS users, Aug 2012.

Swift Default Apps Login

Learning the bash Shell (O'Reilly 3rd edition)
by Cameron Newham
Bash shell programming, flow control structures, job control.

Mac OS X for Unix Geeks
by Brian Jepson, Ernest E. Rothman
The book to buy if you already know UNIX, Sept 2008.

Learning Unix for OS X Mountain Lion: Going Deep With the Terminal and Shell
By Dave Taylor
Take a friendly tour of the Unix command line and 50 of the most useful utilities, Oct 2012.

Apple Pro Training Series: OS X Support Essentials
by Kevin M. White
Apple-certified book on macOS Mountain Lion.

MacOS and iOS Internals by Jonathan Levin
A 'Russinovich level' detailed reference to the kernel and internals of macOS.

AppleScript : The Definitive Guideby Matt Neuburg
An in-depth guide to AppleScript, 2nd Edition 2006.

Package Managers for macOS

MacPorts
A vastly larger number of packages available, owing to its maturity.
Philosophy of keep everything fully separate, by default installs to /opt/local, which usually needs to be created.
It does not rely on MacOS shipped libraries.
MacPorts can be installed to your home directory, so multiple users of the machine can have different setups.
To install GNU coreutils, the GNU tools will have a ‘g’ prefix - i.e. ls will be gls:
sudo port install coreutils
To install GNU coreutils and override (not replace) the default names: [x]
sudo port install coreutils +with_default_names
Written in TCL.

Homebrew
By default installs to /usr/local though you may prefer something like ~/Homebrew this is not recommended.
Packages are generally one or two iterations behind MacPorts, due to their dependence on MacOS shipped libraries.
Doesn't require sudo, geared towards ease of use.
To install GNU coreutils [x]:
brew install coreutils
Hosted on GitHub, written in Ruby.

Saagar Jha has posted a useful comparison of MacPorts and Homebrew.

Deployment Tools

Jamf - Endpoint management for Apple devices.
Dosdude installer - Install macOS on old (unsupported) macs. [Howto]

Command Line tools

Command Line Developer Tools for macOS
Xcode, Additional Tools for Xcode, Font/Graphics/Hardware tools for XCode, ODBC Administrator Tool.
To install, either run a command like gcc or make which will prompt to download if needed or explicitly run xcode-select --install and then choose Install
Alternatively, login to https://developer.apple.com/download/more/ and download the DMG files directly, this is often faster.

Duf - Disk Usage/Free Utility.
FileMon - Log and respond to filesystem events.
OS X Recovery Disk Assistant - Repair disks or reinstall macOS.
pyheif - Python interface to libheif library, convert HEIC images to jpg.
rdfind - Find duplicate files.
Rudix - A collection of pre-built Unix software delivered as packages for macOS by Rudá Moura.
smartmontools - SMART hard drive monitoring.

Applications

Apple GUI Utilities /Network tools can be found in /System/Library/CoreServices/Applications
App compatibility matrix of 7,000+ apps from roaringapps.com
AbiWord - Word Processor.
Acorn - Affordable Graphic Design.
AirPort Utility - Manage Wi-Fi network and AirPort base stations.
AnyBar - A scriptable colour indicator for the macOS menubar.
Amadeus Pro - Audio editor.
Angry IP scanner - network scanner for network administrators.
AppCleaner- Delete application/preference pane files.
Appify - Script that creates Mac apps from shell scripts.
Apple Remote Desktop - Screen sharing plus remote install (Software Distribution).
ArtRage - Paint tool for kids.
Ardour.org - Record Multi-track digital audio.
Audacity - Audio editor and Recorder.
AudioHijack - Capture streaming audio.
Audirvana - Audiophile music player for MacOS.
BBEdit - Text Editor.
BinaryAge - TotalFinder, Spaces & DS_Store management.
BitCom FreeSee - Browse & preview pics and graphics.
Blender - 3D graphics.
Brackets - Open source HTML/CSS code editor.
Brightness Slider - Brightness control from the menu bar (free).
SimplyBurns - Burn CDs & DVD's.

cabextract - Free Software for extracting Microsoft cabinet files.
Caffeine - Prevent your Mac from automatically going to sleep.
Carbon Copy Cloner - Clone/backup hard drive - bootable backup solution for the Mac.
pCalc - Calculator - A fully featured scientific calculator for MacOS and iOS.
Cog - fork1 (Christopher Snowhill), fork2 (Dimitry Mamburu) minimalist music player.

DiskWarrior - Disk Repair.
Doug's Scripts - This Tag That Tag - Swap/Copy iTunes metadata.
dvdbackup - $brew install dvdbackup - Rip DVD's from the command-line.
MyDVDedit - modify the content of a DVD.
DupeZap - Search and remove duplicate files.

F3 (Fight Flash Fraud) - Test flash card capacity/performance to verify claimed specifications.
FastScripts - run scripts with a keyboard shortcut.
FFmpeg - Audio/video encoder.
Find Any File - Find files that Spotlight doesn't, includes bundles/packages/folders that are excluded from Spotlight search.
Font Finagler - Font Cache Cleaner.
FlySketch - Screen shots with selections/highlights etc.
FreeCAD - Sketch 2D shapes and create high quality drawings / 3D models.
Front and Center - Utility to bring all the windows that belong to an application to the front, without clicking the Dock.
FTP - Cyberduck
FTP - Transmit (Panic)
Gemini - Duplicate file finder.
GIPHY Capture - GIF Maker
Gimp - GNU Image Manipulation Program.
Glimpse-editor - GIMP with a better name (beta)
GPG Tools - Encryption for Apple Mail messages and files.
Graphic Converter - File format conversion and basic editing.
Grand Perspective - Graphical disk usage utility.
Handbrake - DVD Ripper.
HTML Tidy - Check and fix HTML and XML files.

iA Writer - Distraction free word processor.
iExplorer - Copy music to an iPhone or iPad in disk mode, (like Android).
ImageMagick - Edit/Convert bitmap images(PNG, JPEG, GIF) on the command line (scripts).
imageOptim - Remove image metadata & compress images without losing quality. (Free/Open Source).
iMazing - Transfer and save files to/from any iOS device, also back up the device.
Inkscape - Vector Graphics (Illustrator).
iPhone Enterprise support - Apple.
iOS configurator - Mass configure and deploy iPhones and iPads.
iStat Menus - System Monitor.
iStumbler - Test WiFi & Bluetooth connections.
iTerm2 - Terminal with Search and Replay.
iTunes LAME encoder.
iTunes - CopyTrans Manager - Windows application that allows quick drag & drop from PC to iDevices.
Jamf - Mobile Device Management software for Apple devices.
Java for OS X 2015-001 - Deprecated version of Java 6, typically required only for Adobe Apps.
Karabiner - Keyboard customizer for macOS.
KeyCodes - Display code for each keyboard key.
Keynote - Apple Presentation software (free).
Keynote-Extractor - Convert Keynote to HTML.
LiteIcon - Change OS X finder icons.
Little snitch - Monitor applications 'dialling home' e.g. connections from syspolicyd when running an unsigned script.
LuLu - Free, open-source firewall that can block unknown outgoing connections.
m-cli - Command line administration of macOS.
MTR (Mac the Ripper) - DVD Ripper.
Max - Rip CD's in Maximum quality & convert audio file formats.
Menu Meters - view CPU, memory, disk & Network activity in the menu bar.
Micro - Terminal-based text editor that aims to be easy to use and intuitive.
MPV.io - A fork of mplayer2 and MPlayer.

Default Apps Mac

Numi - Calculator for MacOS (free)
OBS Studio - Free and open source software for video recording and live streaming.
Open Office/Libre Office - MS Office compatible productivity suite (Free).
OmniGroup - Drawing/Diagrams, Dictionary, Outliner (note taking), Project Management.
OnyX - Maintain and optimize macOS.
macOS High Sierra (10.13.x) requirements 4.8 GB download.
Pacifist - Open pkg /dmg files e.g. macOS install disks and extract files.
Parallels.com - Run win 32 programs in parallel with macOS apps (Amazon link ).
Pashua - Aqua dialog windows for your scripts.
PCalc - Fully featured scientific calculator for macOS and iOS.
PDFtk - Command-line tool for processing PDFs.
Photoshop Elements - Basic photo editing and organisation.
PhotoRec - Data recovery software - hard disk, CD-ROM & Memory Cards.
PictureCode - Noise Reduction.
Pinboard.in - Bookmarking + app SimplePin
Pixelmator Pro - Image editor (alternative to PhotoShop).
Pixelmator - Image editor (alternative to PhotoShop) for older macs.
PGP for Mac - GPG Suite - secure 0003communication and file encryption.

Quicksilver - App/document launcher (free).
Quick Look plugins - Various - via howtogeek.com
Quit All Open Applications - Automator.

RawTherapee - Raw image processing.
Reeder - RSS reader (compatible with feedly).
Reggy - Regular Expression tester/viewer.
Rename files - NameChanger / NameMangler / ABetterFinderRename
Remote iOS app - Control iTunes on a mac from a remote iPhone/iPad.
Remote Desktop for Mac - Microsoft RDP connect to Windows machines. Also Royal TS
Sequel Pro - Web development (MySQL).
ScreenGrabber - Convert movie to stills.
SwitchResX - Change Screen resolutions.
Scrivener - Writers studio (Outliner).
Shotcutapp - free, open source, cross-platform video editor.
ShinyWhiteBox - Video capture (record Window/Desktop).
Simon - Server monitoring.
SMARTReporter - HD monitor.
Smultron - Text editor with code highlighting.
Solarized theme for macOS Terminal.
SoX - Sound processing command line utility.
TotalSpaces - Spaces manager.
StartupSound - Adjust volume of the boot chime.
Subler - Edit Video metadata, remove facebook tracking numbers (.mp4/.mov).
SuperDuper - Disk cloner, create a bootable recovery disk.
SwiftDefaultApps - MacOS Preference pane to view and change default file associations.
Swinsian - A better iTunes.
TeamViewer - Screen sharing/Remote control (Mac/PC/Linux).
Telestream - Screen recording/editing, pro media player/editor.
TenderApp - Helpdesk.
TimeMachineEditor - change the default one-hour backup interval of Time Machine.
TinkerTool - User interface tinkering.
Tiny Player - The notepad.exe of Mac music players.
Transmit - The best FTP client.
TripMode - Bandwidth monitor for MacOS (for tethered laptops).
Ukelele - Keyboard Layout Editor.
The UnArchiver - A more capable replacement for 'Archive Utility.app' (BOMArchiveHelper) Free.
Unison Newsgroup reader - Now free.
UTM - Virtualization for ARM64 or x86/x64 operating systems.
Unpkg - Tailor installation packages to allow manual install.
Vanilla - Hide menu bar icons.
Vienna - RSS reader.
Vim for Mac - Classic text editor.
VLC Audio/Video Player - MP3, wma, DVD, Flac etc.
Ulysses - Writing app.
Video Codecs - Handy list from the University of Berlin.
VMWare Fusion - Run Wintel & Mac apps side-by-side.
VueScan - Scanner Software.
WebP utilities - encode/decode WebP animated images, Google.
WiFi Explorer Lite - Wireless network discovery - identify channel conflicts and Wi-Fi network configuration problems.
Windows Flip4Mac - QuickTime plugin for Windows Media files (.wmv).
Witch - Application/Window switcher.
World Clock - Screensaver.
Xee - Image viewer (Preview replacement).
XLD - X Lossless Decoder - Rip audio CDs with no errors, can also convert audio file formats.
Xcode Developer Tools package - Apple programming tools and utilities for Mac, iPhone, and iPad.
youtube-dl - Video download script.

Many of the commercial apps above are also available in the Apple App Store. Apple requires all App Store users to accept legal restrictions in the iTunes EULA and DRM (copy protection). When buying software direct you will be subject to different, generally less restrictive terms of use but will also miss Automatic Updates through through the App Store.

Find more apps at MacUpdate.com or TinyApps
iOS Apps

SS64 Discussion Forums

“Real artists ship” ~ Steve Jobs (attr)

I've been reading a lot online about custom URL handlers / custom protocol handlers such as:

I get that you can tell the system that a particular program is able to handle a certain scheme / protocol with the Info.plist file:

But if there are multiple applications that are capable of opening the same URL handler, such as mailto: how do you specify which one you want the system to use?

There were some references to utilities like the More Internet preference pane which no longer seems to be available from the author's site. I did find it online by Googling but it seems a bit shaky – like it was written for an older OSX – perhaps Tiger.

I haven't been able to find information on how to set the URL handler for protocols and custom protocols. I'm assuming there is a plist file somewhere that I can edit – or maybe there is a newer, better utility that works well with Mountain Lion?