Sip for grabbing colors and building palettes.
ImageOptim for lossless compression of images and gifs. Lossy settings available as well for more intense compression. This is super useful for web development and design.
RightFont the best font manager for Mac.
Plenty of other font managers out there. I used to use Font Explorer X Pro, but a year or two ago switched to RightFont and it’s been great cause now I can sync my library between my laptop and desktop.
Just wanted to throw this in as well, in case it might be useful to some, Fontbase is a great free font manager where you can do the same plus you can categorize and do other stuff as well and Right Font is what I use and it has served me well, I can definitely say this has the custom text-ability and many other great features. the con is it's only for Mac. what more nice about these font managers is that you do not need to install the fonts to use them, you can just link them to the software and activate or deactivate the fonts you need so fonts won't take too many resources than necessary to function. I hope this helps someone out. let me know if you have any questions and ill be happy to answer from what I know.
No, webfonts only "live" within the realm of WebKit. Also, macOS has no native support for WOFF or WOFF2 (there is/was a 3rd party QL plugin, though to preview WOFF in Finder, IIRC).
RightFont might be worth a try. It supports online font libraries like Google Fonts, TypeKit etc..
You could try something like Right Font (not free) or Font Base (free but not quite as sophisticated as Right Font). Not plugins but really great font managers.