Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Invision - Prototyping and collaboration for design teams
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Sketch - Professional digital design for Mac.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.