Talkus - Chat with your website users from Slack
Cryptgeon - Securely share self-destructing notes
Chatlio - When you have a business to run, your average instant messaging software just will not do. You need an internal presence upon which your entire team can collaborate on. Read more about Chatlio.
BURN.link - Send secure, encrypted, self-destructing messages
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Burner Note - Burner Note is a free, ad-free and open sourced service for sending secure text based notes that are completely erased from existence once they've been read.