IGdm is Desktop messaging app for Instagram. You can simply continue your chats from your phones to your computers.
Franz 2.0 is a desktop app that puts messaging services altogether in one place. It can combine apps like WhatsApp, Slack, Facebook Messenger, WeChat, HipChat, Skype and a lot more. You can even use multiple accounts for the Facebook Messenger - mix your business profiles and your private ones if you need to.