Franz is the ultimate king to rule in the stupid messy war of IM. (Franz means King in Austria as where it developed). It combines all web-available messaging platforms into one, and hence iMessage is not invited. With multiple account support, you can easily to switch between personal Facebook messages and business talking on Slack.
Additional support of major email platforms (Gmail, Yahoo, Outlook), Franz spares endless tab pages from your browser and connects with local push notification as well.
| Franz, Windows / Mac / Linux, Free