SloPro - Shoot video at a high speed then play it back in 1000 FPS slow motion.
Looper – Boomerang Video Converter - This app can convert the camera roll video into a loop video to funk up the Instagram feed.
Slow Motion Video FX - Slow down your videos with a single click. Adjust speed, zoom in, slow down a certain part of your video. Even speed up. All online, no account required
Live GIF - Convert live photos to GIF
Slow motion Video Editor - Slow Motion Video Editor is an application through which you can slow down the motions of your usual video.
GifLab - The easiest way to create GIFs on your iOS device