Slack is a free messenger that provides its users with unlimited opportunities for collective communication. Perfect for group chats with a lot of people.
In addition to exchanging simple text messages, Slack allows you to make personal and group audio and video calls, display the screen during a video conference, exchange files, pictures and active links. Also, group chats provide the possibility of sending personal and collective selective messages, which will be visible only to their addressees.
Besides, there are many useful additional functions in the program. For example, the possibility of restricting the rights of participants, setting up a notification system after a specified interval of time with the setting of a "quiet clock" during which notifications will be disabled, as well as archiving messages, quick search by messages, etc. In addition, the program has its own hosting for storing files and supports work with many well-known Internet services: Dropbox, GitHub, Google Drive, Google Hangouts, Google Docs, Trello, Twitter, Heroku, Jira, MailChimp, etc.
Messenger Slack allows you to create an unlimited number of rooms for communication, both public and private. All chats can be quickly found in the general list using the search function by name.