Quick Link
https://github.com/diegogangl/reflow
Pricing
free
The Reflow addon allows you to change the FPS of an existing animation. For example if you have a 24 FPS animation that you want to use in a 30 FPS project, this addon can help you turn the 24 FPS action in to a 30 FPS one with minimal quality loss.
Link to the creators website
Reflow addon for Blender - Sinestesia
Think you’re ready for 60fps video? I’ve just released a free addon for Blender to help you with that.

sinestesia.co