A free app for Android, by Rustem Kakimov.
Mooltik: Storyboard & Animate is ideal for a storyboard for a music video or short cartoon, or an animatic for a film. It can be considered a cross between a video editor and a sketching program.
Some features of this app include tools for basic drawing. You will be given time for each scene and frame to exact durations. There is also looping animations and independent timelines function as layers like action in the background can be animated separately from the main action. Also includes dialogue or other descriptions when annotating scenes. You have the option to add music and export the animatic file as an mp4.