Applications for Mac OS X, developed in Objective-C.
This playbook installs and configures most of the software I use on my Mac for web and software development. Some things in macOS are slightly difficult to automate, so it can't do everything, but it does do a lot, and helps me keep multiple Macs' configuration synchronized.
Quick Resizer is the fastest and simplest app for resizing your images on a Mac.
In the past few years, when wanting to simply take a large picture and reduce it to a specific dimension for a website or app, I would find myself opening up Photoshop, saving for web, changing the dimensions, and quitting Photoshop. This operation took at least 10-20 seconds (even on my speedy SSD-based MacBook Pro!), and at least five or six clicks and button presses.