Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Zeplin - Collaboration app for UI designers & frontend developers
Invision - Prototyping and collaboration for design teams
Mightytext - Send & Receive SMS Text Messages from your computer. Sync'd with your Android #
ActiveWords - Auto correct on steroids
ProtoPie - ProtoPie is the easiest tool used to turn your UI/UX design ideas into highly interactive prototypes for mobile, desktop, web, all the way to IoT.