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.
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
Zulip - Chat for distributed teams. Zulip combines the immediacy of real-time chat with an email threading model. With Zulip, you can catch up on important conversations while ignoring irrelevant ones.
RingCentral Video - Live life unlimited. Free video meetings and team messaging in one app that works the way you do.