Telegram

Telegram is a messaging platform that caters to individuals, organizations, and businesses. In addition to exchanging text messages, images, and files, Telegram also allows for voice and video calls. The platform also provides high security through end-to-end encryption and self-deleting messages.

Particularly exciting for businesses, however, are the Telegram Bot API, with which developers can create programs that use the Telegram Messenger as an interface, as well as the Telegram API and TDLib, which can be used to create custom Telegram clients.

Telegram and both APIs are available for free.