Apps with 'Multiple Account support' feature
Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free. It is like SMS, but more powerful.
Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
A digital notebook application that gives people one place to gather notes and information. .
Pidgin is an easy to use, multi-protocol chat client client used by millions. Connect to AIM, MSN, Yahoo, XMPP, and more chat networks all at once.
Wire is the most secure collaboration platform featuring messenger, voice, video, conference calls, file-sharing, and external collaboration –all protected by the most secure...
Tutanota is a free and open source web-mail client that focuses on privacy and security. It has open source iOS and an Android apps.
Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!
Open source Android email client with support for multi-folder sync, keyboard shortcuts, and more.
Part of the Microsoft Office Suite, Outlook is a personal information manager that lets you manage your e-mail, calendar, contacts, and tasks.
Authy is a simple way to manage two-factor authentication accounts. Authy supports Gmail, Dropbox, LastPass and thousands of other sites.
Free, open source and cross platform messaging and emailing app that combines common web applications into one.
Video game library manager and launcher with support for 3rd party libraries like Steam, GOG, Origin and Uplay, providing one unified interface for your games.
eM Client is a full featured e-mail client with a modern and easy to use interface. eM Client also offers calendar, tasks, contacts and chat.