CONV. - Convert YouTube video to MP3, GIF or MP4
ezgif.com - Ezgif.com is simple online gif maker and toolset for basic animated gif editing.
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
Instagiffer - Create GIFs from anything!
Yout - YouTube to Mp3 Converter
Gifox - Delightful GIF Recording and Sharing App for macOS