I used the Sketch "Delicious" free UI Kit for a food recipes app. It includes 11 pixel-perfect screens. I just added Proto.io interactions and created a great prototype! This Delicious UI Kit was designed by Robert Anitei Sketch source: https://www.sketchappsources.com/free-source/1765-delicious-ui-kit-sketch-freebie-resource.html

This Splash screen prototype shows a vector animation of a headphone made in After Effects. Use the Bodymovin plugin that exports a JSON file and can be dropped right into Proto.io.

The Flipboard animation created using states.

Hi I tried imitating the Trello's interaction to move tiles/cards between different lists.

Basic To Do prototype based on: https://www.sketchappsources.com/free-source/3625-basic-to-do-app-design-sketch-freebie-resource.html

Safe/Combination lock