Mac: There are so many good GIFs out in the world that it's hard to keep track of them all. If you prefer local storage for your favourites, AirGif organises your collection for you. It also shares it with other uses to create a massive GIF library.
You point AirGIF at your GIF folder and it shares all those GIFs with other users of the app. You can search for other GIFs with different tags and download them to use on your own. There's a point system built into downloading GIFs, but you can earn free points just by sharing your own library or tagging GIFs. It all happens right in your menubar so it's out of the way when you don't need it and easily accessible when you quickly need the perfect reaction GIF. If you're making your own GIFs all the time, this is pretty handy way to catalogue them.