Skype for Slack - Move your slack discussions to a group skype call
Clyp - Clyp is the easiest way to record, upload and share audio. No account required.
Aircall Now - Make voice calls inside Intercom Messenger 📞💬
Audio Hijack - Record any audio, with Audio Hijack!
Calls on Slack - Make voice calls in Slack
Loopback by RogueAmoeba - Get all the power of a high-end studio mixing board, right inside your Mac!