Panic's Nova Editor is an alternative to WeBuilder, EditPlus and Dreamweaver...and hands down the best HTML, CSS and PHP editor for Mac -- succeeding the now dead Coda 2; Nova's UI looks minimalistic, but the program is far from it and you have plenty of features a click of a mouse away:has syntax highlighting, internal preview, code-folding, code-completion, a powerful color-editing tool and all the features you find in premium editors like Dreamweaver. The price ($99) is a bit steep, but this app is worth every single penny and more.
Pixelmator Pro is an actual Photoshop alternative in many tasks; it's fairly light-weight but almost as features-packed as Photoshop, so much so that it has become my primary tool to make transparent pngs. The UI has a tiny learning curve, but once you've gone past that (it doesn't take long) it's a must-have app for any macOS user.
Color Slurp is imo the free color picker for Mac; unobtrusive, super-easy to use and very lightweight, the best feature in both is the magnifier for picking any color from the screen; it's very precise and a must-have for every web designer working on macOS. The app has a (pretty cheap) Pro paid version, but all you need is already in the free version.
AppCleaner does exactly what its name says: it gets completely rid of any program app you no longer want to have on your Mac, deleting not just the program files but all those hidden leftovers files and folders who would clutter your hard-drive; all you have to do is drag and drop the app and AppCleaner does all the work for you. You don't have to worry about anything else getting deleted by mistake, as the apps only picks and deletes the files linked to the unwanted program and nothing else. The app is completely free - there is a paid alternative, but in my opinion AppCleaner work as good as that.
The Unarchiver is the best utility to decompress both zip and rar folders on Mac; it doesn't allow you to view the contents of an archive without first unzipping it first, but if you don't care for that feature, The Unarchiver is perfect for you. It's super easy to use and super light-weight, and definitely awesome Mac alternatives to Winzip and Winrar.
Paragon NTFS is a small, cheap (it only costs $20) and extremely useful app that allows you to use any external HDD on your Mac without having to reformat the hard-disk; with this installed, you can read, write, delete and just work with any hdd as if you were on Windows. There is an alternative called Tuxera NTFS but, based on reviews I read as well as my experience, Paragon is definitely the best...and an absolutely recommend program.