RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
ProtonMail - Secure email with absolutely no compromises. Get your free encrypted email account today.
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
GPGMail - GPGMail is an open source plugin for Apple Mail.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
ElectronMail - Unofficial desktop app for ProtonMail and Tutanota end-to-end encrypted email providers