Number To Whatsapp - A utility tool which lets your start a Whatsapp conversation without saving the contact of the said person first.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
BetterChat for WhatsApp - Gorgeous new full-featured WhatsApp client for the Mac.
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
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.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.