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

A halloween project i have put together using the Proto.io Halloween icon set: https://proto.io/freebies/free-halloween-icons/

This app allows you to call loved one and the emergency services in to clicks. If you travel overseas this app is for you. It tells you tips of what to do in certain situations and you are able to enable GPS so the emergency services are able to see where you are.